Sorry, but after I took the bold off of the top line as you said, the line isn't connected...it's the little dash marks w/that tiny space in between. Also, I cannot get the extra line after the title to go away. I clicked double space and tried to erase the extra line with no luck.
thanks!
Nikki
Wednesday, October 28, 2009
Tuesday, October 27, 2009
Confidence Interval (CI)
Someone from the class asked about confidence interval...
In order to understand confidence interval, you have to understand standard error first. When you run a simple/linear regression test on SPSS, one of the output table should contains standard error for your regression model. You will also see that the standard error falls under "unstandardized coefficients", which means that it is an unstandardized value.
Standard error (SE) is pretty much a self-explanatory term... obvious, it has something to do with error. Do you still remember the error that we are talking about in research model? So, whenever you have to infer your test analyzes results to the population, you need to count in the error because you're using sample in your research study rather than the whole population. SE is what you want to add or subtract from the predicted score (y variable). As regression is trying to find out whether the x variable predicts the y variable or not, you can try to guess what score you will get for the y variable by providing a score for the x variable. When you want to predict the y variable to the population, you have to add or subtract the SE from the predicted score to a range of score for the possible score of y in the population.
Let's get back to CI, APA publication manual strongly recommends us to report the 95% CI for any inferential statistics. When you say 95%CI, that means you are sure that 95% of the time you predicted score for the y variable falls within the CI. For example, let's say your SE is 1.50, and the predicted y value is 100. For 95%CI, you're sure that 95 out of 100 guesses you will get a score between 98.50 (100-1.50) and 101.5 (100+1.50) for your y variale in the population.
I hope the explanation of CI help you get through the homework.
In order to understand confidence interval, you have to understand standard error first. When you run a simple/linear regression test on SPSS, one of the output table should contains standard error for your regression model. You will also see that the standard error falls under "unstandardized coefficients", which means that it is an unstandardized value.
Standard error (SE) is pretty much a self-explanatory term... obvious, it has something to do with error. Do you still remember the error that we are talking about in research model? So, whenever you have to infer your test analyzes results to the population, you need to count in the error because you're using sample in your research study rather than the whole population. SE is what you want to add or subtract from the predicted score (y variable). As regression is trying to find out whether the x variable predicts the y variable or not, you can try to guess what score you will get for the y variable by providing a score for the x variable. When you want to predict the y variable to the population, you have to add or subtract the SE from the predicted score to a range of score for the possible score of y in the population.
Let's get back to CI, APA publication manual strongly recommends us to report the 95% CI for any inferential statistics. When you say 95%CI, that means you are sure that 95% of the time you predicted score for the y variable falls within the CI. For example, let's say your SE is 1.50, and the predicted y value is 100. For 95%CI, you're sure that 95 out of 100 guesses you will get a score between 98.50 (100-1.50) and 101.5 (100+1.50) for your y variale in the population.
I hope the explanation of CI help you get through the homework.
Good Plagiarism Q
This was in a comment, and I want to bring it out to the main blog because i have a feeling people aren't checking the comment sections. Christie asked:
"I am scared to plagarize. there is only so many ways you can say variable 1 and variable 2 are correlated. i dont want to get in trouble for saying something clearly, which happens to be the same way someone else did too. . . tips?"
You just now did a paraphrase Christie! I didn't write anything about correlation on mine. But, if you want more examples, that will come with reading articles. The more you read, the more you'll get the gist of your own style, because you'll have a deeper concept. That's probably the best thing i can tell you. actually, i asked the same thing last year...it's posted a ways down the blog, and Mari gave us good advice::
"I would strongly recommend that you read all the examples ...Read them carefully, understand how they are written, and then put them aside. Write your own write up, and do not consult the examples while you are writing. If necessary, refer back to the examples after you are finished writing to check and see that you included all important information. Don't actually look at the examples while you are writing, though, because that makes not plagiarizing very, very difficult."
Hope that helps!
"I am scared to plagarize. there is only so many ways you can say variable 1 and variable 2 are correlated. i dont want to get in trouble for saying something clearly, which happens to be the same way someone else did too. . . tips?"
You just now did a paraphrase Christie! I didn't write anything about correlation on mine. But, if you want more examples, that will come with reading articles. The more you read, the more you'll get the gist of your own style, because you'll have a deeper concept. That's probably the best thing i can tell you. actually, i asked the same thing last year...it's posted a ways down the blog, and Mari gave us good advice::
"I would strongly recommend that you read all the examples ...Read them carefully, understand how they are written, and then put them aside. Write your own write up, and do not consult the examples while you are writing. If necessary, refer back to the examples after you are finished writing to check and see that you included all important information. Don't actually look at the examples while you are writing, though, because that makes not plagiarizing very, very difficult."
Hope that helps!
APA Write ups! (Renewed)
Hello All. So, we finally have some clarification about what to include in the write-up and where!
A sample write up (although one I am presently making up as I go) will look as follows:
A linear regression was used to test the hypothesis that time in minutes would predict understanding. The overall model proved significant in that R = .97, F(1, 222) = 579.32, p < .001. As time in minutes increased, understanding also increased (B = 125.23, SEB = 0.25, β = .97, p < .001, 95% CI [123.23, 127.23]).
Until we find otherwise, we are going to report the CI with the coefficients that it relates to (the Betas) and NOT with the R statistics (like in the example given from page 117 of the APA manual), mainly because that is where SPSS is pulling the CI from, so that is how we would report it. PLEASE NOTE! You still need to report the proper statistics from the coefficient table, the 6th edition DID NOT take those away!!! Also...this is not the only way you can write a write up, make sure you are not plagiarizing the examples that any of us have given you! Mainly, just make sure that you include all the necessary elements of the write up and from there the style will come!
Hope this helps! Thanks for your patience as we figured this out!
A sample write up (although one I am presently making up as I go) will look as follows:
A linear regression was used to test the hypothesis that time in minutes would predict understanding. The overall model proved significant in that R = .97, F(1, 222) = 579.32, p < .001. As time in minutes increased, understanding also increased (B = 125.23, SEB = 0.25, β = .97, p < .001, 95% CI [123.23, 127.23]).
Until we find otherwise, we are going to report the CI with the coefficients that it relates to (the Betas) and NOT with the R statistics (like in the example given from page 117 of the APA manual), mainly because that is where SPSS is pulling the CI from, so that is how we would report it. PLEASE NOTE! You still need to report the proper statistics from the coefficient table, the 6th edition DID NOT take those away!!! Also...this is not the only way you can write a write up, make sure you are not plagiarizing the examples that any of us have given you! Mainly, just make sure that you include all the necessary elements of the write up and from there the style will come!
Hope this helps! Thanks for your patience as we figured this out!
Saturday, October 24, 2009
Answers for unanswered question from Monday Review Session last week
During the Monday Review Session last week, several questions were unanswered, but here are the answers.
1. What does F ratio tell you? What does it have to do with regression?
- F ratio tells you how big the explained variance and unexplained variance
- F ratio determines whether your regression model (in the case of regression) is significantly different from the null model (zero) or not
- the significance level tells you whether your regression model is significantly different from zero or not
2. What does d.f.s. mean in lecture 6 powperpoint slide 27?
- d.f.s = degress of freedoms
- referring to slide 26 ANOVA table (SPSS output), df for "total" is equal to the sum of df for "regression" and df for "residual"
3. Do I have to know assumptions of regression now (see lecture 6 powerpoint slide 18)?
- no, don't worry about it if you don't understand it now. Sung will revisit this topic with a lecture later on in the course.
1. What does F ratio tell you? What does it have to do with regression?
- F ratio tells you how big the explained variance and unexplained variance
- F ratio determines whether your regression model (in the case of regression) is significantly different from the null model (zero) or not
- the significance level tells you whether your regression model is significantly different from zero or not
2. What does d.f.s. mean in lecture 6 powperpoint slide 27?
- d.f.s = degress of freedoms
- referring to slide 26 ANOVA table (SPSS output), df for "total" is equal to the sum of df for "regression" and df for "residual"
3. Do I have to know assumptions of regression now (see lecture 6 powerpoint slide 18)?
- no, don't worry about it if you don't understand it now. Sung will revisit this topic with a lecture later on in the course.
Homework 2 help
Some people from your class asked about how to report statistical results in APA style, here is a sample that you can follow, but you need to paraphrase it in order to use it in your homework.
To report your model is significant or not (for all kinds of regression):
Significant relationship between number of cars and air pollution index was found, that the number of cars can predict air pollution index, R2 = .88, F(1, 33) = 236.32, p < .001, 95% CI [.02, .22].
To report the direction of your model (for simple regression only):
Increasing the number of cars was related to more severe air pollution, B = 3.87, SEB = 0.25, β = .94, p < .001.
As always, it is worthwhile to look up APA Publication Manual (6th ed.) because it provides critical information on how to do a write-up correctly for your homework. :)
Good luck! ;-)
To report your model is significant or not (for all kinds of regression):
Significant relationship between number of cars and air pollution index was found, that the number of cars can predict air pollution index, R2 = .88, F(1, 33) = 236.32, p < .001, 95% CI [.02, .22].
To report the direction of your model (for simple regression only):
Increasing the number of cars was related to more severe air pollution, B = 3.87, SEB = 0.25, β = .94, p < .001.
As always, it is worthwhile to look up APA Publication Manual (6th ed.) because it provides critical information on how to do a write-up correctly for your homework. :)
Good luck! ;-)
Friday, October 23, 2009
Need clarification on the assignment
Do we also need to plot the linear regression line and show the equation for it?
Thursday, October 22, 2009
Monday Review Session Location
Some people suggested to meet in the computer lab for Monday review session; however, we will be meeting at the same old location, Payton 100 (right by the Garth) at 5:30pm. Thanks.
Wednesday, October 21, 2009
A word on early Article Reviews
Here's the deal. You can turn in your article review early like Dr. Kim said. We your TA's will look over ONE and return it to you with marks but NO GRADE WILL BE ENTERED. All required article reviews will still need to be turned in by the normal dead line. This means if you have an early review returned to you, YOU MUST TURN IT IN AGAIN to receive credit. Also, if you have turned in more than one article for early review only one will be reviewed but both will be returned to you so you can make corrections on both. If you have turned in two different types of articles we will still only "test grade" one. Sorry if this disappoints, we have to draw a line somewhere =). Most of the issues that people will have relate to formatting and are more or less the same for both types of reviews.
Thanks!
Your TA's
Thanks!
Your TA's
Tuesday, October 20, 2009
Single space is recommended.
Yes, I know. Double space is the standard. However, we want to save trees. Thanks.
You can submit your very first article review for a check and get it back with no grade or no penalty, if you want to. However, you need to submit it soon because TAs will be inundated with many article reviews as the first deadline (first 4 article reviews by either Nov. 2nd or 3rd) is approaching. Please note that TAs will be reading about 150 article reviews in early November.
You can submit your very first article review for a check and get it back with no grade or no penalty, if you want to. However, you need to submit it soon because TAs will be inundated with many article reviews as the first deadline (first 4 article reviews by either Nov. 2nd or 3rd) is approaching. Please note that TAs will be reading about 150 article reviews in early November.
article review questions..again.
I know that the new edition of the APA manual says we have to double space everything. Is that true for our reference list? Do we double space after each period?
Monday, October 19, 2009
Another Article Review Question
I was asked:
"do we have to include a copy of the article with our review? And, how do you tell the difference between an empirical article and the other one"
(a) No, you do not have to include a copy of the article. If we need something, that's what the reference is also used for, you're most likely getting it on EBSCO, so if we need it we will be able to search for it on EBSCO.
(b) My fellow TAs and/or Sung can add to this second part if they think of better clarifications. I think that The best way is to see whether or not there were any tests run. If you see numbers, it is most likely empirical. If you see any statistics, this is most likely empirical. Theory-based articles will just base off of theory, and so when you read through it and write the review you'll use those other headings found on the second page of the example to clarify (i.e., Reference, Major Premise, Development of the Argument, Population From Which the Theory was Developed, Strengths and Limitations of the Paper, Relevance for the Current Question)
Hope this helps...other TAs and Sung may help more.
"do we have to include a copy of the article with our review? And, how do you tell the difference between an empirical article and the other one"
(a) No, you do not have to include a copy of the article. If we need something, that's what the reference is also used for, you're most likely getting it on EBSCO, so if we need it we will be able to search for it on EBSCO.
(b) My fellow TAs and/or Sung can add to this second part if they think of better clarifications. I think that The best way is to see whether or not there were any tests run. If you see numbers, it is most likely empirical. If you see any statistics, this is most likely empirical. Theory-based articles will just base off of theory, and so when you read through it and write the review you'll use those other headings found on the second page of the example to clarify (i.e., Reference, Major Premise, Development of the Argument, Population From Which the Theory was Developed, Strengths and Limitations of the Paper, Relevance for the Current Question)
Hope this helps...other TAs and Sung may help more.
Article Review
Your pseudonym or real name goes to the "Strudel...." You can use the same pseudonym that was used for your homework. If you want to use a different pseudonym, please let me know.
You should follow the 6th edition. I strongly recommend you have a personal copy of the APA Publication Manual (6th ed.). You can buy one at the Fuller Bookstore. Today (Monday) I had a brief review session on article review with the Monday class and am going to have another one with the Tuesday class. If you are familiar with the 5th edition, you need to educate yourself with the difference between the 6th and the 5th editions. Please visit the following website for a brief review on that (Thank you so much, Grace!).
http://www.apastyle.org/manual/whats-new.aspx
If you have any further questions, please let me know.
You should follow the 6th edition. I strongly recommend you have a personal copy of the APA Publication Manual (6th ed.). You can buy one at the Fuller Bookstore. Today (Monday) I had a brief review session on article review with the Monday class and am going to have another one with the Tuesday class. If you are familiar with the 5th edition, you need to educate yourself with the difference between the 6th and the 5th editions. Please visit the following website for a brief review on that (Thank you so much, Grace!).
http://www.apastyle.org/manual/whats-new.aspx
If you have any further questions, please let me know.
Sunday, October 18, 2009
Hey Grace,
So we just put our pseudonym, but then what? For the sample, it has Toaster Strudel, Sandwich, Spaghetti...do we need to type three things there or just our pseudonym?
Also, do we need to inlcude the doi in listing our reference? I have the newest edition of the APA manual, and I'm unclear if I need to provide another number. I've retreived most of my articles from the library's online databases.
Thanks!
So we just put our pseudonym, but then what? For the sample, it has Toaster Strudel, Sandwich, Spaghetti...do we need to type three things there or just our pseudonym?
Also, do we need to inlcude the doi in listing our reference? I have the newest edition of the APA manual, and I'm unclear if I need to provide another number. I've retreived most of my articles from the library's online databases.
Thanks!
Okay I'll admit it...
On the quiz I could not remember how to calculate IQR. Can you review the equation? ~Amber B.
Article Reviews
Just to clarify (again), our article review should be one page, single spaced and follow the example for the section titles?
Also, at the top of the sample review, it has "toaster Strudel, Sandwich, Spaghetti". What goes there? Is that we're are pseudonyms go?
Thanks!
Also, at the top of the sample review, it has "toaster Strudel, Sandwich, Spaghetti". What goes there? Is that we're are pseudonyms go?
Thanks!
Thursday, October 15, 2009
Article Review
Hi TA's,
Let me know if this isn't true, but I think I remember hearing you guys say that you are willing to look at our first Article Reviews to make sure we did them correctly before we turned them in.
Yes? No? Maybe? :)
Thanks for all your help so far!
Let me know if this isn't true, but I think I remember hearing you guys say that you are willing to look at our first Article Reviews to make sure we did them correctly before we turned them in.
Yes? No? Maybe? :)
Thanks for all your help so far!
Wednesday, October 14, 2009
question about review slides
It may be a bit late, but I noticed a discrepancy between the review notes (slide 6) and the lecture notes (lecture 2, slide 14). The lecture slides say that the saturated model has no explanatory power but the review slides say that the saturated model has the highest explanatory power.
Just wanted to point that out. My feeling is that the lecture notes are correct though I may be wrong.
Tuesday, October 13, 2009
Review Follow-up
Hello All!
I officially posted the slides I used in the review last night (Monday) onto Portico. Feel free to access them.
HOWEVER please note the disclaimer! These are just a simple review! Although they are taken directly from Sung's lecture notes, they are only supposed to supplement all of his lecture powerpoints! Just because something is included in the review powerpoint does not mean it will definitely be on the test. Also, just because something was excluded from the powerpoint, does not mean it will be excluded from the test. Study wisely!
If you have questions, feel free to blog them or email for us to blog! Also, the Wednesday review session will most likely cover these powerpoint review slides as well for those who missed the Monday review.
Hope it helps!
--TAs
I officially posted the slides I used in the review last night (Monday) onto Portico. Feel free to access them.
HOWEVER please note the disclaimer! These are just a simple review! Although they are taken directly from Sung's lecture notes, they are only supposed to supplement all of his lecture powerpoints! Just because something is included in the review powerpoint does not mean it will definitely be on the test. Also, just because something was excluded from the powerpoint, does not mean it will be excluded from the test. Study wisely!
If you have questions, feel free to blog them or email for us to blog! Also, the Wednesday review session will most likely cover these powerpoint review slides as well for those who missed the Monday review.
Hope it helps!
--TAs
Sunday, October 11, 2009
Boxplot Question
This question just in...
"Can someone tell me how to create the box and whiskers plot."
Do the following...
Graphs --> Legacy Dialogs --> (Boxplot) --> (make sure to select simple boxplot AND "summaries of separate variables") --> (click over desired variable) --> OK
That should do the trick.
Sorry the "summaries of separate variables" was not in the original explanation.
Hope that helps =)
~A TA who is up too late on a Sunday night!
"Can someone tell me how to create the box and whiskers plot."
Do the following...
Graphs --> Legacy Dialogs --> (Boxplot) --> (make sure to select simple boxplot AND "summaries of separate variables") --> (click over desired variable) --> OK
That should do the trick.
Sorry the "summaries of separate variables" was not in the original explanation.
Hope that helps =)
~A TA who is up too late on a Sunday night!
HW #3 Z-score calculation
I want you to calculate the Z-scores of the values (16, 18, 20, ...) using the means and standard deviations of x and y. The values (16, 18, 20, ...) has nothing to do with the ids (representing rows) of the homework data set. If you have any questions, please let me know. Thanks.
Saturday, October 10, 2009
Weekly Review Session Time and Venue
Hi everyone,
Starting from next week, we (TAs) are offering two review sessions every week. Here are the times and venues.
1. Monday 5:30pm (Payton 100)
2. Wednesday 6pm (Psych. Building 120)
We will make these review sessions to quiz review sessions when quiz is around the corner. Otherwise, we will normally just go over some difficult parts of the lecture or answer whatever questions you bring to the review sessions. If you have any questions on your homework, please feel free to blog your questions here, we'll try to get back to you asap. Have a good weekend!
~TAs
Starting from next week, we (TAs) are offering two review sessions every week. Here are the times and venues.
1. Monday 5:30pm (Payton 100)
2. Wednesday 6pm (Psych. Building 120)
We will make these review sessions to quiz review sessions when quiz is around the corner. Otherwise, we will normally just go over some difficult parts of the lecture or answer whatever questions you bring to the review sessions. If you have any questions on your homework, please feel free to blog your questions here, we'll try to get back to you asap. Have a good weekend!
~TAs
Friday, October 9, 2009
Saving Trees
There were a few of you interested in turning article reviews electronically. Dr. Kim will have to make the final call on this one but for now plan on printing them out and turning them in hard copy. Using pseudonym's might make it hard to do it on line. That and there's enough new technology to figure out for this class already, working with one of the electronic services at this point would probably get in the way of the course content.
~Andy
~Andy
Correlation and Covariance
We just realized that we did not include commands for finding correlation and covariance in SPSS. Here they are...
Finding corretation and covariance,
Analyze ---> Correlate--> Bivariate --> Select Variables --> Options --> New Window pops up --> select "cross-product deviations and covariances -->OK -->OK
For the scatter plot,
Graphs --> Legacy Dialogue --> Scatter plot --> select variables to "x-axis" and "y-axis" --> OK
To add line of best fit,
double click on scatter plot on the output window, click the left fifth icon on the bottom tool bar, make sure it's on "linear" mode". The line of best fit should be on the scatter plot after clicking the icon.
Hope this helps!
~ your TAs
Finding corretation and covariance,
Analyze ---> Correlate--> Bivariate --> Select Variables --> Options --> New Window pops up --> select "cross-product deviations and covariances -->OK -->OK
For the scatter plot,
Graphs --> Legacy Dialogue --> Scatter plot --> select variables to "x-axis" and "y-axis" --> OK
To add line of best fit,
double click on scatter plot on the output window, click the left fifth icon on the bottom tool bar, make sure it's on "linear" mode". The line of best fit should be on the scatter plot after clicking the icon.
Hope this helps!
~ your TAs
Thursday, October 8, 2009
single space recommended
I know APA requires double-space. However, I recommend single-space for the article review to save trees! Thanks.
Sung
Sung
General question about the homework
Dr. Kim told us to attach work on the homework, but I wasn't quite sure whether he only wanted the graphs or also the way I calculated the z-score.
Clarifying points
YES, there WILL be a review session this Monday October 12 at 5:30 but the location has not been determined yet. Sung is searching for a room for us.
Also, as a follow-up about the article reviews. If you prefer to get our feedback from one before you do them all, feel free to test it out and we'll grade it and get it back so you hopefully won't make the same mistakes on the rest of them. Personally, I highly suggest trying to do one early so that you get the feel for it and also get the rubric down. (And it will take some of the load of the end of your quarter, which i know is quite bulky!)
Hope all is well! Hopefully see you tomorrow (friday) for the spss review!
Also, as a follow-up about the article reviews. If you prefer to get our feedback from one before you do them all, feel free to test it out and we'll grade it and get it back so you hopefully won't make the same mistakes on the rest of them. Personally, I highly suggest trying to do one early so that you get the feel for it and also get the rubric down. (And it will take some of the load of the end of your quarter, which i know is quite bulky!)
Hope all is well! Hopefully see you tomorrow (friday) for the spss review!
Article Review
Hi,
Let me clarify about article reviews. If there is anything confusing, please refer to the sample article review. For example, I am going to explain later in the class, but for now b (analyses listed) & c (findings described) in the syllabus should be combined into b (findings) in the sample. Also, d (sample described) in the syllabus is equal to c (population) of the sample.
If you have any questions, please let me know. Thanks.
Let me clarify about article reviews. If there is anything confusing, please refer to the sample article review. For example, I am going to explain later in the class, but for now b (analyses listed) & c (findings described) in the syllabus should be combined into b (findings) in the sample. Also, d (sample described) in the syllabus is equal to c (population) of the sample.
If you have any questions, please let me know. Thanks.
Wednesday, October 7, 2009
Questions about Journal Articles
Hi TAs,
Thank you for the info about review sessions!
I have a few questions about the journal articles:
1. The sample article review posted on portico appears to be single spaced and is about 1 page in length, but APA formatting is often double spaced and Dr. Kim noted in class the article reviews should be 2 or 3 pages. Could you confirm spacing and length requirements for article reviews?
2. The sample article review posted contains 5 italicized "substantive components" (hypothesis, major findings, population, etc) and the syllabus contains 6 components - the additional one is "analyses listed." Should this analyses section also be included and if so, what info should it contain?
Thank you!
Melissa
Thank you for the info about review sessions!
I have a few questions about the journal articles:
1. The sample article review posted on portico appears to be single spaced and is about 1 page in length, but APA formatting is often double spaced and Dr. Kim noted in class the article reviews should be 2 or 3 pages. Could you confirm spacing and length requirements for article reviews?
2. The sample article review posted contains 5 italicized "substantive components" (hypothesis, major findings, population, etc) and the syllabus contains 6 components - the additional one is "analyses listed." Should this analyses section also be included and if so, what info should it contain?
Thank you!
Melissa
Article Review
Someone from this class asked about article review...
Here are some tips...
Here are some tips...
- Dr. Kim has posted an example of article review on portico which you can refer to
- Make sure you include all the headings that are on the example. You can choose to copy the headings from the example (with exact wording, we won't count it as plagiarism). Of course, you're welcome to paraphrase them if you find some better ways to say them.
- Make sure you are following the APA Style Manual in terms of citation and writing style because you will get points off if you did not follow it. For example, never start a sentence with a number (eg. 50), but spell it out (Fifty). Also, make sure you have 1 inch for all margins. You can find APA Style Manual in the Hubbard Library or Integration Library (on reserve) if you don't own one. Here is a helpful website on APA style: http://www.docstyles.com/apacrib.htm
- For any information that the authors should have included in certain sections of the article, make sure you point it out under the section "Flaws of Study and Limitations to Generalizability". For population, you have to include number of participants, gender, enthicity, and age. For example, if the researchers forgot to include the age of participants, make sure you report it.
- Try your best to keep your article review in a page, it's okay if you really need to go over a page
- Make sure you will use quotation marks and include page number(s) if you are quoting something from the article; otherwise, paraphrase everything else.
- Some of you might have learn to put 2 spaces after a period, there is only 1 space between a period and the beginning of a sentence.
- This homework is help you to build up your literature review if you have decided what you want to do for your master/dissertation. If you don't have an area of interest, no worries, you can take this opportunity to explore your interests. So, try to stick with what you are really interested in and demonstrate it under "Relevance for the Current Question"
- In the "reference" section, make sure where to put a space, some periods after authors' initials are followed by a space, some are not. Also, know when to capitalize and when not to, especially for the title of the article.
- You don't need a cover/title page for this homework, use the same layout in the example
- Under "Major Findings" section, you do not need to report descriptive or inferential statistics, rather, you just need to report what kind of test analyzes the researchers used and summarize the findings.
- If you are doing the article review on a qualitative study, follow the headings that are listed on the second page of the example article review posted on portico.
**Review Sessions!!**
HELLO ALL!
So! After great consideration and hearing your response to review sessions, we have decided on a few things.
First of all, we would like to host a SPECIAL review session to intro SPSS and answer any SPSS and/or first homework related questions. This will be THIS Friday, October 9, 2009 at 1:00 pm in the research computer lab in the library. But if you could, come EARLY (5-10 minutes) because the Lab we are in has a login that the tech guy will need to help us with. If you're wondering where the lab is, the front desk should know.
FYI, Grace and I will be using a sample data set that is different from your homework, but are willing to answer any questions regarding the homework and how it works out on SPSS. You will just have to go back and use your own dataset when completing the homework.
Ok, on to the NORMAL/WEEKLY review sessions. We have decided that Monday at 5:30pm (in a location to be announced soon) and Wednesday at 6:00pm (in the psych building room 120) are going to be the normal sessions. I think there are about 4 or 5 of you that this may not work with, and that is fine, if you want a review session FEEL FREE to set one up with one of us, we all enjoy doing this and would be able to better cater to your individual needs.
I hope that this helps out as you expect. If there are any suggestions that any of you may have, feel free to blog it or email one of us for us to blog.
p.s. don't miss the great info about SPSS info in the post just before this one...it gives exact ways to compute with SPSS that will help before the review!
So! After great consideration and hearing your response to review sessions, we have decided on a few things.
First of all, we would like to host a SPECIAL review session to intro SPSS and answer any SPSS and/or first homework related questions. This will be THIS Friday, October 9, 2009 at 1:00 pm in the research computer lab in the library. But if you could, come EARLY (5-10 minutes) because the Lab we are in has a login that the tech guy will need to help us with. If you're wondering where the lab is, the front desk should know.
FYI, Grace and I will be using a sample data set that is different from your homework, but are willing to answer any questions regarding the homework and how it works out on SPSS. You will just have to go back and use your own dataset when completing the homework.
Ok, on to the NORMAL/WEEKLY review sessions. We have decided that Monday at 5:30pm (in a location to be announced soon) and Wednesday at 6:00pm (in the psych building room 120) are going to be the normal sessions. I think there are about 4 or 5 of you that this may not work with, and that is fine, if you want a review session FEEL FREE to set one up with one of us, we all enjoy doing this and would be able to better cater to your individual needs.
I hope that this helps out as you expect. If there are any suggestions that any of you may have, feel free to blog it or email one of us for us to blog.
p.s. don't miss the great info about SPSS info in the post just before this one...it gives exact ways to compute with SPSS that will help before the review!
SPSS HELP E-mail
Hey Everyone,
This is coming to you both on the Blog and via e-mail. Future things will all be posted on the blog but until we're all on the blog there will be a few more mass e-mails. Sorry for the inbox clutter.
We are working to put together a review session specifically for SPSS intro on Friday. Location will be the classroom in the library (ask at the library front desk). Time TBA.
We will be focusing on what you need to know to do the homework, class notes will be discussed NEXT week at the normal review sessions. However, we only know SPSS and any questions on how to use "R" need to be directed to Dr. Kim. Please bring your questions to review or post them to the blog if you can. If you can't make the review or aren't able to work the blog yet feel free to e-mail one of us and we'll do everything we can short of doing it for you =). We will be working from an example data set on Friday that does not match the homework assignment.
In case you don't / can't come here's a play by play on how to use SPSS...
The following is taken from Dr. Mari Clements notes with permission...
To obtain estimates of central tendency... ( 3 different ways)
After loading data set into SPSS...
Click on Analyze (one of the options in the top toolbar)
Then select... Descriptive Statistics --> Descriptives --> (click over variables of interest) --> Options --> (check desired stats) --> Continue --> OK
Click on Analyze (one of the options in the top toolbar)
Then select... Descriptive Statistics --> Frequencies --> (click over variables of interest) --> Statistics --> (check desired stats) --> Continue --> OK
Click on Analyze (one of the options in the top toolbar)
Then select... Descriptive Statistics --> Explore --> Dependent List --> (click over variables of interest) --> OK
For Interquartile range: Follow the above directions.
For the graphs/charts you need...
Graphs --> Legacy Dialogs --> (Select desired plots) --> (If necessary, specify type, e.g. simple boxplot) --> (click over desired variable) --> OK
Analyze --> Descriptive Statistics --> Frequencies --> (click over variables of interest) --> Charts --> (check desired stats) --> Continue --> OK
Analyze --> Descriptive Statistics --> Explore --> Dependent List --> (Click over variables of interest) --> Plots --> (Check desired plots) --> Continue --> OK
For Creation of histograms with normal curve imposed:
Analyze --> Descriptive Statistics --> Frequencies --> (click over variables of interest) --> Charts --> Histogram (select "with normal curve") --> continue --> OK
*** you will need to select "simple boxplot" in order to make the required boxplot chart
To make "Z-scores" with SPSS (you can calculate these by hand)
Analyze --> Descriptive statistics --> Descriptives --> (Click over varibles of interest) (select "save standardized values as variables --> OK
We hope that makes sense. Please e-mail or blog any questions. You can also bring your questions to review on friday.
~Your TA's =)
This is coming to you both on the Blog and via e-mail. Future things will all be posted on the blog but until we're all on the blog there will be a few more mass e-mails. Sorry for the inbox clutter.
We are working to put together a review session specifically for SPSS intro on Friday. Location will be the classroom in the library (ask at the library front desk). Time TBA.
We will be focusing on what you need to know to do the homework, class notes will be discussed NEXT week at the normal review sessions. However, we only know SPSS and any questions on how to use "R" need to be directed to Dr. Kim. Please bring your questions to review or post them to the blog if you can. If you can't make the review or aren't able to work the blog yet feel free to e-mail one of us and we'll do everything we can short of doing it for you =). We will be working from an example data set on Friday that does not match the homework assignment.
In case you don't / can't come here's a play by play on how to use SPSS...
The following is taken from Dr. Mari Clements notes with permission...
To obtain estimates of central tendency... ( 3 different ways)
After loading data set into SPSS...
Click on Analyze (one of the options in the top toolbar)
Then select... Descriptive Statistics --> Descriptives --> (click over variables of interest) --> Options --> (check desired stats) --> Continue --> OK
Click on Analyze (one of the options in the top toolbar)
Then select... Descriptive Statistics --> Frequencies --> (click over variables of interest) --> Statistics --> (check desired stats) --> Continue --> OK
Click on Analyze (one of the options in the top toolbar)
Then select... Descriptive Statistics --> Explore --> Dependent List --> (click over variables of interest) --> OK
For Interquartile range: Follow the above directions.
For the graphs/charts you need...
Graphs --> Legacy Dialogs --> (Select desired plots) --> (If necessary, specify type, e.g. simple boxplot) --> (click over desired variable) --> OK
Analyze --> Descriptive Statistics --> Frequencies --> (click over variables of interest) --> Charts --> (check desired stats) --> Continue --> OK
Analyze --> Descriptive Statistics --> Explore --> Dependent List --> (Click over variables of interest) --> Plots --> (Check desired plots) --> Continue --> OK
For Creation of histograms with normal curve imposed:
Analyze --> Descriptive Statistics --> Frequencies --> (click over variables of interest) --> Charts --> Histogram (select "with normal curve") --> continue --> OK
*** you will need to select "simple boxplot" in order to make the required boxplot chart
To make "Z-scores" with SPSS (you can calculate these by hand)
Analyze --> Descriptive statistics --> Descriptives --> (Click over varibles of interest) (select "save standardized values as variables --> OK
We hope that makes sense. Please e-mail or blog any questions. You can also bring your questions to review on friday.
~Your TA's =)
Wednesday, September 30, 2009
We have a blog now.
If you have any questions or anything, you can come here and share it with us. If you need help with using this blog, please let me know. Thanks.
Sung
Sung
Thursday, December 11, 2008
Reporting Significance Levels
John asked,
When reporting significance level at the .05 level, if my value is .051 can I report as p = .051 (using three decimal places to show approximation)?
When reporting significance level at the .05 level, if my value is .051 can I report as p = .051 (using three decimal places to show approximation)?
Wednesday, December 10, 2008
Missing Values
Mari said earlier that
I have 2 predictors and 1 outcome.
In the event that the outcome and one predictor is missing values do I delete the case even if the other predictor has an value listed?
Absolutely you should drop any participant who is missing both predictors and outcome.
I have 2 predictors and 1 outcome.
In the event that the outcome and one predictor is missing values do I delete the case even if the other predictor has an value listed?
Assumptions
Can you test assumptions for a categorical variable? This doesn't seem to make sense, because looking at residuals for a contrast-coded variable doesn't seem to provide useful information. So maybe rather than can you test the assumptions, my question is am I supposed to?
Also, for a moderated model, do you check assumptions for the moderator variable? I know there was an earlier post that said you don't have to check assumptions of the predictor for each level of the moderator, but I'm unclear about checking the moderator as its own variable.
Also, for a moderated model, do you check assumptions for the moderator variable? I know there was an earlier post that said you don't have to check assumptions of the predictor for each level of the moderator, but I'm unclear about checking the moderator as its own variable.
Tuesday, December 9, 2008
reflecting part 2
I noticed that after I had reflected my data and transformed it, the relationship became a positive one, where betas went from negative to positive. I do conceptually understand why it turned out this way, but in my results write up, do I indicate that after i have reflected and transformed my data, there was a significant negative relationship in transformed units, and then report the positive betas that I got from the regression?
mirroring
The distribution of my residuals were slightly negatively skewed, and when I mirrored and transformed my outcome, the histogram still showed a slight negative skew. Can this be normal, or did I overlook a step in my transformation process?
Thank you for all the lightning fast responses!
Thank you for all the lightning fast responses!
Violation of homoskedasticity?
Sorry if it is not okay to ask this outright, but does this look okay? I went ahead and tried the transformations and it got progressively worse. Should I include in my write-up that I tried to transform but it got worse, or should I just say this is "good enough" and only include my first tests of assumptions?
Vanishing Post?
I was responding to a post, and blogger wigged out on me. Suddenly my response and the original post were both gone. If your post vanished, and you still need the answer, please repost!
How Much Overlap is Too Much?
There have been a couple of blog and backchannel questions about the acceptable degree of overlap between previous homework assignments and the final project.
The general rule is that as long as 51% or more of the model has changed, you are OK. That is,
1. if you are using some of the same variables, but in a different model (i.e., the homework model was an additive hierarchical model and now you are looking at the same variables in a mediated or moderated model), that's OK. (Note that the converse is not true--a mediated or moderated homework model cannot revert to an additive hierarchical model, because in that case, you would have no need to run the regressions, because they were already done in the original homework assignment. That is, regression 3 from a mediated model is exactly what you would run to test an additive model with those variables. Similarly, step 1 of a moderated model is the additive multiple regression model.)
1. if the outcome is the same, but predictor and mediator are different, that’s OK.
2. if one predictor is the same, but a moderator, mediator, or second predictor have been added, and the outcome is different, that's OK.
3. if a mediator is the same, but the predictor and outcome are different, that's OK.
If you aren't sure if your model fits those parameters, feel free to ask, but have patience for the reply. I start jury duty tomorrow and will not have internet access...
The general rule is that as long as 51% or more of the model has changed, you are OK. That is,
1. if you are using some of the same variables, but in a different model (i.e., the homework model was an additive hierarchical model and now you are looking at the same variables in a mediated or moderated model), that's OK. (Note that the converse is not true--a mediated or moderated homework model cannot revert to an additive hierarchical model, because in that case, you would have no need to run the regressions, because they were already done in the original homework assignment. That is, regression 3 from a mediated model is exactly what you would run to test an additive model with those variables. Similarly, step 1 of a moderated model is the additive multiple regression model.)
1. if the outcome is the same, but predictor and mediator are different, that’s OK.
2. if one predictor is the same, but a moderator, mediator, or second predictor have been added, and the outcome is different, that's OK.
3. if a mediator is the same, but the predictor and outcome are different, that's OK.
If you aren't sure if your model fits those parameters, feel free to ask, but have patience for the reply. I start jury duty tomorrow and will not have internet access...
Transformations
I know that you just do a transformation when both assumptions (homoskedasticity and normality are violated), but what do you need to do when the two violated assumptions are linearity and homoskedasticity (a different pair)and normarlity is perfect. I found in my notes about polinomial regression or adding a squared term to the regression. Do I need to do that? If yes, HOW? If not, I will have 2 assumptions violated. Does that mean that this model does not work?
transformed results write up
would it be possible for us to see an example of an APA results section where the data was transformed? or is it just a matter of just indicating that the results were transformed and discussing the numbers in transformed units?
comparing negative Betas
Hello, I have another question regarding negative betas:
For my mediated model, if the B from the first regression (predictor->outcome) was, let's say -0.55, and the B of predictor->outcome on the third regression was -0.02. Would I still treat this as a situation where the B from the first regression is "greater" than the B from the third? Since mathematically, -0.55 is a smaller value than -0.02, but in terms of relationships, -0.55 still represents a greater amount of change per unit of X?
For my mediated model, if the B from the first regression (predictor->outcome) was, let's say -0.55, and the B of predictor->outcome on the third regression was -0.02. Would I still treat this as a situation where the B from the first regression is "greater" than the B from the third? Since mathematically, -0.55 is a smaller value than -0.02, but in terms of relationships, -0.55 still represents a greater amount of change per unit of X?
A question regarding my model
Will be acceptable to do a moderated model with sex as moderator, but using different predictor and outcome varibles not used in the last assigment?
Mediated Model
I have a question regarding my mediated model.
My unstand. B in R3 (-0.015) is not lower than B in R1 (-0.17), but the 3 regressions showed that each is significant (p-values of R1, R2, and R3 are less than .001). This shows that there is no mediation? What's going on?
And when I put this into the Sobel's test (for negative betas), the test statistic shows to be -8.48, but the p-value is 0. So there's a significant level of mediation, right?
These two results are not supporting one another.
Another question: for the Sobel's test statistic, do I regress Mediator (M) to Outcome (O) separately to find the B and SE? Or do I just use the M and O figures from my R3, which is (P and M on O)?
Thanks!
My unstand. B in R3 (-0.015) is not lower than B in R1 (-0.17), but the 3 regressions showed that each is significant (p-values of R1, R2, and R3 are less than .001). This shows that there is no mediation? What's going on?
And when I put this into the Sobel's test (for negative betas), the test statistic shows to be -8.48, but the p-value is 0. So there's a significant level of mediation, right?
These two results are not supporting one another.
Another question: for the Sobel's test statistic, do I regress Mediator (M) to Outcome (O) separately to find the B and SE? Or do I just use the M and O figures from my R3, which is (P and M on O)?
Thanks!
Transformed Variables and the Sobel Test
To add to Chris's question,
If we need to do a transformation in a mediated model, do we have to do anything to the unstandardized beta's before we use them for the Sobel test or can we use them as is?
Thanks,
Andrew
If we need to do a transformation in a mediated model, do we have to do anything to the unstandardized beta's before we use them for the Sobel test or can we use them as is?
Thanks,
Andrew
Exam 3 at Front Desk
Feel free to drop by and take a look at your exam, and where you currently stand in the class. Note that your final article reviews are NOT included in that grade estimate (just because the TAs are working on final exams and projects too, not because of any special thing about these assignments).
Monday, December 8, 2008
I am working in a moderated model were I need to run separate regressions for each level of the moderator variable. I want to check my assumptions, but I don't know if I need to use the unstandarized predicted values and residuals of the separate regressions or I need to run a single regression for all cases and use those unstandarized predicted values and residuals. In other words, do I need to check assumptions separate for each level of the moderator (2 graphics per assumption)?
negative betas and sobel's test
I was using the sobel's test website to test a mediated model, but i noticed that when one of the B's i put in the equation was negative, the significance values became what looks to me like 1-p? (i.e., if i had a 2-tailed p value of .95 with the negative B, it would turn into .05 if i changed that B to positive.) How would significance be determined/reported for this situation? And would I report the sobel's test statistic as negative as well?
thanks!
thanks!
Assumptions for a Mediated Model
Hello friendly and helpful TAs (and/or Mari),
I have a question related to GLM assumptions for a mediated model. When we utilize Baron and Kenny's three model approach for testing mediation, there are three separate regressions performed to test the mediation; during these steps the 'predictor' and 'outcome' variables change according to what you want to analyze. (The relationship of the true predictor to true outcome, relationship of true predictor to mediator, and relationship of both true predictor and mediator to true outcome).
So, my questions:
1) Do we have to test each seperate relationship for GLM assumptions? I assume that at least the first two models do need to be tested, as the relationship of the predictor to outcome and the relationship of the predictor to mediator would have to conform to the assumptions to be valid, but I am unsure of the last model.
2) If assumptions are not met and a transormation needs to be tested on the outcome variable, should I transform for each step of B & K's mediation approach? If I do, this makes interpretation sort of hairy in the second step of the model, as the "outcome" variable to be transformed is no longer the outcome of true interest. Or should I just transform my true outcome on the first regression? In the case that I need to transform for all steps of B & K's approach, how do I interpret the relationship at each step?
Gracias,
Chris
I have a question related to GLM assumptions for a mediated model. When we utilize Baron and Kenny's three model approach for testing mediation, there are three separate regressions performed to test the mediation; during these steps the 'predictor' and 'outcome' variables change according to what you want to analyze. (The relationship of the true predictor to true outcome, relationship of true predictor to mediator, and relationship of both true predictor and mediator to true outcome).
So, my questions:
1) Do we have to test each seperate relationship for GLM assumptions? I assume that at least the first two models do need to be tested, as the relationship of the predictor to outcome and the relationship of the predictor to mediator would have to conform to the assumptions to be valid, but I am unsure of the last model.
2) If assumptions are not met and a transormation needs to be tested on the outcome variable, should I transform for each step of B & K's mediation approach? If I do, this makes interpretation sort of hairy in the second step of the model, as the "outcome" variable to be transformed is no longer the outcome of true interest. Or should I just transform my true outcome on the first regression? In the case that I need to transform for all steps of B & K's approach, how do I interpret the relationship at each step?
Gracias,
Chris
clear-up on small detail
I know that we aren't allowed to use any model previously used in homework assignments or lecture, but we can still use a variable that was used in those assignments, right?
For example, would I be able to hypothesize that perceived humor and morality would predict global self worth? (Not actually using this model for my assignment, but global self worth is a variable we used in other assignments, but since the overall model uses different variables to accompany global self worth, I can go ahead with it?)
thanks!
For example, would I be able to hypothesize that perceived humor and morality would predict global self worth? (Not actually using this model for my assignment, but global self worth is a variable we used in other assignments, but since the overall model uses different variables to accompany global self worth, I can go ahead with it?)
thanks!
Failed Assumptions
If when you test your assumptions and cannot pass no matter which transformation applied, can you still use that regression include in your write up that it didn't pass assumptions so that the data cannot be interpreted reliably? Do you want us to start the complete experiement over again with new variables until we find something that works?
Which residuals to use?
I am trying to test the assumptions for a hierarchical multiple regression. After I create the new variables (in this case, square root transformed), do I re-run my assumptions by plotting the new square root variables with the residuals that were generated from my first regression, or do I save new residuals by running the same hierarchical mutliple regression with the new transformed variables and then re-run the assumptions using those new residuals that were generated from the second regression?
Sunday, December 7, 2008
Testing Assumption of Homoskedasticity
After creating my scatterplot, i would like to test the ratio of highest to lowest variance. I am not sure how to split the file- the options within this drop down menu do not seem to include the ability to separate the predictor (or is it the predicted values i use?) into meaningful levels. Is there another step i am missing? I messed up my data file once already trying to accomplish this and had to red0 everything all over again :-(
Also, is there a generally accepted cut-off point when you have missing data (i.e. if the missing data represents < 5% of the total sample) that is applied when deciding to omit participants? Predicting values has already proven to be difficult due to more missing data in the alternative variables used.
Also, is there a generally accepted cut-off point when you have missing data (i.e. if the missing data represents < 5% of the total sample) that is applied when deciding to omit participants? Predicting values has already proven to be difficult due to more missing data in the alternative variables used.
Thursday, December 4, 2008
Final Project: Missing Values
My outcome variable is missing 8 values. I used a multiple regression with my outcome and two other variables that are significantly related to my outcome but aren’t my variables of interest. Yet, my outcome variable is still missing 8 values because those 8 cases were also missing values for the two significantly related variables. Next, I used the regression equation (Transform à Computer Variable) and formed a “predictedoutcome” variable a follows:
Predictedoutcome – B + (B * variable) + (B * variable)
My new predictedoutcome variable is still missing 8 values.
Where shall I go from here? Am I supposed to continue to look for additional variables that are significantly related to my outcome variable? Should I drop a case (subject) if there are missing values on all three of my variables of interest (i.e., my two predictors and outcome)?
Also, can you please specifically explain how to merge two variables on SPSS? I tried merging two variables in “Compute Variable” under the “Function group” but received an error messsage.
Thank you.
Predictedoutcome – B + (B * variable) + (B * variable)
My new predictedoutcome variable is still missing 8 values.
Where shall I go from here? Am I supposed to continue to look for additional variables that are significantly related to my outcome variable? Should I drop a case (subject) if there are missing values on all three of my variables of interest (i.e., my two predictors and outcome)?
Also, can you please specifically explain how to merge two variables on SPSS? I tried merging two variables in “Compute Variable” under the “Function group” but received an error messsage.
Thank you.
Wednesday, December 3, 2008
levels of moderation
Hello, I hope it's not too late to ask this question...
For categorical moderators, what does it mean exactly when you regress the outcome on the predictor for each level of the moderator? Would they be separate simultaneous multiple regressions where you regress predictor and level 0 of the moderator on outcome, and regress predictor and level 1 of the moderator on outcome?
For categorical moderators, what does it mean exactly when you regress the outcome on the predictor for each level of the moderator? Would they be separate simultaneous multiple regressions where you regress predictor and level 0 of the moderator on outcome, and regress predictor and level 1 of the moderator on outcome?
Tuesday, December 2, 2008
note discrepancy
I found a discrepancy between the typed out notes and the slides, and could only speculate as to which one was correct. In the notes (for "Prediction and Validation", 3rd page, last sentence above Validation of models) it says
"As sample size increases and number of predictors INCREASE, these three types of R^2 grow closer..." (emphasis added).
The slides however (slide 17 i believe) says these three types "merge as sample size N increases and number of predictors (k) DECREASES"
It makes sense to me that k should decrease because an increase will take away from degrees of freedom, decreasing power. But i don't want to jump to conclusions...which is right? Thanks!!!
"As sample size increases and number of predictors INCREASE, these three types of R^2 grow closer..." (emphasis added).
The slides however (slide 17 i believe) says these three types "merge as sample size N increases and number of predictors (k) DECREASES"
It makes sense to me that k should decrease because an increase will take away from degrees of freedom, decreasing power. But i don't want to jump to conclusions...which is right? Thanks!!!
Monday, December 1, 2008
Review Sheet and Final Project Posted
The review sheet for exam 3 and the guidelines for the final project have now been posted to Portico. The TA's will also have copies of the review sheet at this evening's review session.
For those of you who would appreciate individual review sessions, please feel free to sign up for times with the TA's.
For those of you who would appreciate individual review sessions, please feel free to sign up for times with the TA's.
Article Review
I am working on an article review and I came across an article with an author listed his/her name as A. H. Y. Ho. Should I cite his/her name as "Ho, A. H. Y." or "Ho, A. H." in the reference section of the article review? Thanks.
Wednesday, November 26, 2008
article review ?
Ok...for one of my article reviews i have run into a problem...
When searching the results section (and then the rest of the paper!) i could not find the models used specifically stated. I know that they found frequencies, but the rest of their results are simply given in different symbols. I can only speculate (and try to remember) what these symbols mean. A few of the statistics look like this: x^2(l) = 8 54, p < 01 ....which i BELIEVE is chi-squared? Then further down it changes to Z = 3 25, p < 001...which i BELIEVE is z-test?
Are these speculations correct? should i simply state that they didn't give a specific model used in determining results?
If needed, here is the reference for my article:
When searching the results section (and then the rest of the paper!) i could not find the models used specifically stated. I know that they found frequencies, but the rest of their results are simply given in different symbols. I can only speculate (and try to remember) what these symbols mean. A few of the statistics look like this: x^2(l) = 8 54, p < 01 ....which i BELIEVE is chi-squared? Then further down it changes to Z = 3 25, p < 001...which i BELIEVE is z-test?
Are these speculations correct? should i simply state that they didn't give a specific model used in determining results?
If needed, here is the reference for my article:
Egeland, B., & Sroufe, L. A. (1981). Attachment and early maltreatment. Child Development, 52, 44-52.
Monday, November 24, 2008
Review Session Questions...Answered!
Hi all!
As promised, I contacted Dr. Clements to get the answers to questions I wasn't sure about that were asked during tonight's review session.
1. Sobel's Test is reported with the symbol z prime. That is, use a lowercase, italicized z with a tick mark superscripted above it. (If I could get the blog to show it, I would.) If you don't understand from my description, you can see the article that Dr. Clements suggested you look at for an example of writing up mediated models found in an earlier post on the blog.
2. Always, always, always use 2-tailed tests of significance.
3. You do NOT have to include ANY figures for the moderated/mediated models homework. However, IF you do choose to include them, make sure they are formatted according to APA format.
4. Finally, we come to centering. This is important for one of the methods for testing moderated models. If you choose to test it using the method that requires an interaction term, you need to center the continuous predictor variable. Make sure you do this before creating the interaction term. Otherwise, you'll have collinearity issues.
As promised, I contacted Dr. Clements to get the answers to questions I wasn't sure about that were asked during tonight's review session.
1. Sobel's Test is reported with the symbol z prime. That is, use a lowercase, italicized z with a tick mark superscripted above it. (If I could get the blog to show it, I would.) If you don't understand from my description, you can see the article that Dr. Clements suggested you look at for an example of writing up mediated models found in an earlier post on the blog.
2. Always, always, always use 2-tailed tests of significance.
3. You do NOT have to include ANY figures for the moderated/mediated models homework. However, IF you do choose to include them, make sure they are formatted according to APA format.
4. Finally, we come to centering. This is important for one of the methods for testing moderated models. If you choose to test it using the method that requires an interaction term, you need to center the continuous predictor variable. Make sure you do this before creating the interaction term. Otherwise, you'll have collinearity issues.
SPSS GradPack Installation Issues
Bought the gradpack this weekend. I had a lot of problems trying to get the software to work. After waiting 1 1/2 hours for SPSS tech support this morning, it turned out that the company mislabelled their installation authorization codes.
In the gradpack, you will see two authorization codes: SPSS Installation Authorization Code and Amos Installation Authorization Code. For my gradpack, the code for the SPSS Installation Authorization Code is actually the code for AMOS Installation Authorization Code, and vise versa. If you are thinking of purchasing the SPSS software, and you encounter similar installation issues, you might want to try using the Amos code.
The SPSS technician said this problem has been noted and that I wasn't the first person to have this problem. Check with the SPSS technician if you are still having installation issues.
Good luck.
In the gradpack, you will see two authorization codes: SPSS Installation Authorization Code and Amos Installation Authorization Code. For my gradpack, the code for the SPSS Installation Authorization Code is actually the code for AMOS Installation Authorization Code, and vise versa. If you are thinking of purchasing the SPSS software, and you encounter similar installation issues, you might want to try using the Amos code.
The SPSS technician said this problem has been noted and that I wasn't the first person to have this problem. Check with the SPSS technician if you are still having installation issues.
Good luck.
Logistic Regression Yanked
I have decided that it makes more sense to consolidate what we already know about regression than to add another topic...
Sunday, November 23, 2008
Sobel's Test
Regarding to question 2. A., how do we report Sobel's test result in APA format? Is there a specific symbol stand for Sobel's test, such as B stands for unstandardized B? Thank you.
Sobel's Test, Part 2
I think I understand what the diagram on the website means conceptually, but my question is more related to reading the SPSS printout. On my SPSS output for the third regression of question 2, I have three Betas: the constant, and two Betas for the two independent variables I used in the regression. What I'm not sure of is which of these three Betas Sobel's test is asking for.
Saturday, November 22, 2008
Sobel's Test
I'm having trouble figuring out which numbers to use for the online Sobel's Test calculator (http://www.danielsoper.com/statcalc/calc31.aspx). On the website it asks for four values: A, SE of A, B, and SE of B. I figured out where to find A and SE of A (i.e. the Beta and SE of the predictor-mediator regression), but I'm not sure where to find B and the SE of B (i.e. the Beta and SE of the mediator-outcome regression). According to the "Additive, Moderated, and Mediated Models" handout, slide 11, there is no Mediator-Outcome regression, so where do I find the Beta and SE that the Sobel Test is looking for?
Centering in SPSS
i cannot seem to find directions for the keystrokes necessary to center a variable in SPSS. How does one translate the equation into something that SPSS recognizes- i've hit a wall. I've done it manually but am not sure whether or not the results are precise enough.
Friday, November 21, 2008
2 questions
(1) When looking at slide 7 and realizing which test we should complete, i realize that the one we use does not include looking at the interaction. I'm wondering, then, if we still need to do so because in slide 9 the second bullet says that we must interpret the interaction. So, do we still need to look at the interaction term even though it is not discussed in the type of test we are using for question number 1?
(2) In the hw you say that "if" we include figures...this doesn't say that we need to, but should we since it is mentioned in the instructions?
Thanks!
(2) In the hw you say that "if" we include figures...this doesn't say that we need to, but should we since it is mentioned in the instructions?
Thanks!
Betas for interaction model
After adding the interaction term to the second model, it seems unnesscessary to explain the betas for the gender and PAQ variables because they have already been explained through the interaction term interpretation. Is it then necessary to interpret the Betas for gender and PAQ for the second model in the write up after you have already explained the interaction term?
At Long Last
Received from the bookstore
----------------------------------------------------------
Dr. Clements,
The SPSS 17 Grad Pack is now available in the bookstore. We currently have 5 copies for Mac and 3 copies for Windows. Thanks!
Jeremy Mast
Bookstore Floor Supervisor
----------------------------------------------------------
Dr. Clements,
The SPSS 17 Grad Pack is now available in the bookstore. We currently have 5 copies for Mac and 3 copies for Windows. Thanks!
Jeremy Mast
Bookstore Floor Supervisor
Thursday, November 20, 2008
Based on the last question:
Can we use a calculated interaction term for question 1 with gender, by treating gender as continuous?
Furthermore, can we center gender if we have problems with collinearity? Is it okay to center gender?
Furthermore, can we center gender if we have problems with collinearity? Is it okay to center gender?
Wednesday, November 19, 2008
Multiple vs. Linear Regressions
I'm looking at question #1 on the homework and I'm not sure exactly what type(s) of regression(s) to run. According to the PowerPoint slide handout for "Additive, Moderated, and Mediated Models", Slide 7, we are supposed to run three separate regressions:
1. Outcome by Predictor
2. Outcome by Moderator
3. Outcome by Moderator/Predictor Interaction Term
Did I understand this right? Also, are we running three separate linear regressions, or one multiple regression, or some combination of linear and multiple regressions?
1. Outcome by Predictor
2. Outcome by Moderator
3. Outcome by Moderator/Predictor Interaction Term
Did I understand this right? Also, are we running three separate linear regressions, or one multiple regression, or some combination of linear and multiple regressions?
Sample moderation/mediation APA write-up
Looking through the notes, I notice that we do not have a sample for how to write up a moderation or mediation results section like we had for Multiple Regression/Linear Regression. From the notes, I know what moderation and mediation mean, I just don't know how to write them up. I know how to use APA format, I just do not understand how to say what I need to say and what statistics are appropriate for moderation/mediation.
Tuesday, November 18, 2008
Hierarchical Stepwise Regression
What is a hierarchical stepwise regression? Is it as just as "bad and evil" as stepwise regressions? How does it relate to forward and backward entry?
Thank you.
Thank you.
Formula for the Curve
For any assignment curved in any of my classes, the formula is the same:
Individual's score
------------------------- X 100
Highest score in class
In this case, there were a few folks who scored 100 or 92, but I took them off the curve, and used the next highest score (90) as the denominator.
So, if your score had been 80, solving this equation, you would have a score of
80
--- X 100 = 88.8
90
Individual's score
------------------------- X 100
Highest score in class
In this case, there were a few folks who scored 100 or 92, but I took them off the curve, and used the next highest score (90) as the denominator.
So, if your score had been 80, solving this equation, you would have a score of
80
--- X 100 = 88.8
90
Next Quarter ANOVA Sections
The ANOVA class is just like the Regression class in terms of the course sections. The two sections are the same--there is no PhD or PsyD section. Choose the one that fits best with your own work, class, and personal schedule.
Q regarding the article review
Hi,
I read an article using the quantitative reserch review method, and wrote a review under the empirical article review format. I just wonder whether it's ok, or I'd better adopt the theoretical review format.
Thank you.
I read an article using the quantitative reserch review method, and wrote a review under the empirical article review format. I just wonder whether it's ok, or I'd better adopt the theoretical review format.
Thank you.
Monday, November 17, 2008
Recommending normality transformations...
So, the book doesn't recommend the need for transformation if there is a problem with normality (p.46). I think they give a reason for this, but if it's their reason, i don't understand it. They even say that "many regression textbooks" do find this type important. I know transforming is largely subjective...but what is the rule of thumb for this?
Thanks in advance for the clarification!!!
Thanks in advance for the clarification!!!
Saturday, November 15, 2008
Interactive and Mediated Models Homework
The homework assignment is posted on Portico. Note due date change from syllabus.
Wednesday, November 12, 2008
Article Reviews and Next Homework Assignment
So, given that this coming Tuesday has many, many things due, I thought that it might make sense to modify our due dates as follows:
The Article Reviews that were due on Tuesday are now due on Thursday.
The Interactive Models homework that was due on Thursday is now due on the following Tuesday.
I realize that this just redistributes pain rather than eliminating it, but if it helps you to have a couple of extra days, please take them as outlined above.
The Article Reviews that were due on Tuesday are now due on Thursday.
The Interactive Models homework that was due on Thursday is now due on the following Tuesday.
I realize that this just redistributes pain rather than eliminating it, but if it helps you to have a couple of extra days, please take them as outlined above.
df1 = k - 1
Hi, I'm working on question 9 in the review sheet.
When using the equation df1 = k - 1 in regression, is the constant considered one of the predictors so that df1 = k - 1 = 2 (the constant and another predictor) - 1 = 1?
Is this the right way to look at it or should I be taking the class again?
When using the equation df1 = k - 1 in regression, is the constant considered one of the predictors so that df1 = k - 1 = 2 (the constant and another predictor) - 1 = 1?
Is this the right way to look at it or should I be taking the class again?
Monday, November 10, 2008
?? regarding the text
Okay...So, i've been meaning to ask for a while, just never sat down to ask.
The book makes a lot of weird marks above the symbols, and i dont' know what the different marks mean. For example...The predicted value from the model is (symbols that i can't even try to make with word so i'll attempt to explain in words)...Xi with a tilda (~) above it and then β with a ^ above it...
p.48 for reference due to my lack of vocabulary...
So...do these symbols have a meaning? I'm sure they do...so i guess what is the meaning they carry? and is it common to use them?
The book makes a lot of weird marks above the symbols, and i dont' know what the different marks mean. For example...The predicted value from the model is (symbols that i can't even try to make with word so i'll attempt to explain in words)...Xi with a tilda (~) above it and then β with a ^ above it...
p.48 for reference due to my lack of vocabulary...
So...do these symbols have a meaning? I'm sure they do...so i guess what is the meaning they carry? and is it common to use them?
Review Sessions this Week
In addition to our regularly scheduled Monday session at 5 p.m. in room 126 Weyerhaeuser, there is an additional session scheduled for Wednesday at 6 p.m. in room 311 Weyerhaeuser.
(Weyerhaeuser is the official name of the Psych Building...)
(Weyerhaeuser is the official name of the Psych Building...)
Friday, November 7, 2008
Wednesday, November 5, 2008
Sample size & descriptive statistics
I was about to write up my results section for the homework and noticed that the homework handout mentions surveying 240 college students, while my SPSS output looks like it has a sample size of 371, where F(2, 368) = xxx.xx for model 1. Was this a typo on the handout, or am I missing something?
Also, do we need to include descriptive statistics in our results write up? Thanks!
Also, do we need to include descriptive statistics in our results write up? Thanks!
write up
For question 1A, we are asked to report whether adding more predictors will improve the predictability of all of the X variables or not. Do we have to report the R square for each model or do we have to report the R square for the overall model only? When the change of R square between two models is 0.00, does it mean adding extra predictor variable(s) does not improve the prediction? Thanks!
Tuesday, November 4, 2008
question about the write-up
As I am looking at my powerpoint notes, I noticed that the write-up talks about "higher education weakly but significantly predicted lower happiness" and later "Age was also found to signicficantly predict happiness, with older respondents slightly but significantly less happy." I am assuming these are referring to the unstandardized betas and obviously the significance values.
My question is how else to state/explain the differences in unstd. betas as we look at six different variables. I started to say in my own write up that one had a slightly stronger correlation than the other or that the strongest variable correlated was such and such. I'm afriad this is too close to the dreaded "better predicts" that Dr. Clements told us to avoid and that correlated isnt the right description??
Is it important that we differentiate between unstd. betas as we do our write up, or is it enough to say that they all significantly predicted self worth or all but such and such sig. predicted?
Thanks...
My question is how else to state/explain the differences in unstd. betas as we look at six different variables. I started to say in my own write up that one had a slightly stronger correlation than the other or that the strongest variable correlated was such and such. I'm afriad this is too close to the dreaded "better predicts" that Dr. Clements told us to avoid and that correlated isnt the right description??
Is it important that we differentiate between unstd. betas as we do our write up, or is it enough to say that they all significantly predicted self worth or all but such and such sig. predicted?
Thanks...
Transformations PowerPoint Slides
Hi all!
After looking back over the PowerPoint slides from the transformations lecture today, I realized that I made a change to a slide, but forgot to mention it. Your print-out of the slides needs to be modified at one point.
If you look at the first slide on centering, it states "To center: Y i centered = Yi – Mi." It should actually read, "To center: X i centered = Xi – Mi" We only ever center predictors, and X stands for our predictors, while Y stands for our outcome variables. To center, subtract each value of the predictor from the mean of the predictor (or some other meaningful value). Sorry for the confusion.
After looking back over the PowerPoint slides from the transformations lecture today, I realized that I made a change to a slide, but forgot to mention it. Your print-out of the slides needs to be modified at one point.
If you look at the first slide on centering, it states "To center: Y i centered = Yi – Mi." It should actually read, "To center: X i centered = Xi – Mi" We only ever center predictors, and X stands for our predictors, while Y stands for our outcome variables. To center, subtract each value of the predictor from the mean of the predictor (or some other meaningful value). Sorry for the confusion.
What means altering the order of entry of the blocks?
For the second step of the HW, we have to "alter the order of the entry for the blocks of variables". Note it does not say altering the order of variables.I am interpreting "altering the order of the blocks" as we should keep together the variables that were together in a block in the first analysis. In other words, if in block 1 of the first regression I had variables A and B together, in the second regression I will keep A and B together but will entered in step (block) 2,3,4. Is this correct? Should I mix the varibles and create new blocks (for example have varible A in step 3 and B in step 4).
Colinearity and Tolerance
When describing colinearity for part C of question 2, we are using tolerance statistics via SPSS (which have an inverse relationship with with colinearity; e.g., the higher the tolerance value, the less colinear are the variables). SPSS gives tolerance statistics for each variable in every step (or block) of the model. My question: for each specified variable that is excluded (in the first step there are 4, the second, there are 3, and the third, there is 1), does the tolerance stastic associated with that variable refer to colinearity between that variable and the model at that point in time? For example, at Step 1, the tolerance level that is reported for physical appearance is the relationship of colinearity between that variable and the overall model- which up to that point has used intellectual ability and school competence (and therefore only refers to colinearity between these variables used together and physical appearance?) If you could help to deliniate what the tolerance levels mean for each block, it would be helpful.
Chris
Chris
Difference between the first hypothesis and 2-4.
In the write up portion of the assignment should we account for the difference in wording from the first hypothesis and the other three. The first states "expect to predict higher levels of global self-worth", while the other three state "significantly improve prediction of global self-worth". Does "improve" refer to the "prediction" or "global self-worth"?
The way I read it is that "improve" is referring to prediction, so the variables in hypothesis 2, 3, and 4 could all improve prediction for lower self-worth and still prove the hypothesis. Am I reading this wrong?
The way I read it is that "improve" is referring to prediction, so the variables in hypothesis 2, 3, and 4 could all improve prediction for lower self-worth and still prove the hypothesis. Am I reading this wrong?
Multiple Regression Homework: Question 1
Are we running four hierarchical multiple regressions (i.e., 1 - block 1; 2 - block 1 and 2; 3 - block 1, 2, & 3; and 4 - block 1, 2, 3, & 4)? Or, are we running one hierarchical multiple regression (i.e., 1 - block 1, 2, 3, & 4)? The coefficients table yields slightly different values.
Thanks.
Thanks.
Monday, November 3, 2008
hypothesis 1
For the first hypothesis of the Multiple Regression homework, are we using a simultaneous multiple regression to find our answer instead of a heirarchical?
Or are hypothesizing that perceived school competence and intellecutal ability would predict higher global self-worth, holding all other variables constant? So if it were a heirarchical regression, would the independent variables in the first block 0f the heirarchical regression be schcomp and intabil, and the second block all the other variables that we are considering for the assignment?
Or are hypothesizing that perceived school competence and intellecutal ability would predict higher global self-worth, holding all other variables constant? So if it were a heirarchical regression, would the independent variables in the first block 0f the heirarchical regression be schcomp and intabil, and the second block all the other variables that we are considering for the assignment?
Writing Workshop
Please encourage any and all students who are having difficulty with their writing skills to attend our upcoming Writing Workshops, presented by Fuller's Writing Center. By encouraging your students to attend, you will not only help them to improve the quality of their writing, but also potentially save yourself and your TAs some grief in grading papers at the end of the quarter! :) All workshops are taught by Fuller alumna Kathryn Streeter, who came to Fuller with six years of English teaching experience and has, to date, served as a TA for a total of nine classes taught by four different Fuller professors. The workshop schedule is as follows:
Composition Workshop
How to develop a strong thesis statement, form coherent paragraphs, and use supporting evidence appropriately
Friday, November 7, 2008, from 1-3 p.m., in Payton 102
Advanced Composition Workshop
How to develop different kinds of thesis statements, transition deftly between paragraphs, smoothly integrate quoted material, and more!
Friday, November 14, 2008, from 1-3 p.m., in Payton 102
Grammar & Editing Workshop
How to fix common grammatical errors such as inconsistent verb tense, flawed sentence structure, and misplaced punctuation
Friday, November 21, 2008, from 1-3 p.m., in Payton 102
All workshops are FREE, and no RSVP is needed. A packet of helpful materials will be available at each workshop for $5.
Thank you for your help in getting the word out! Flyers will be available in classrooms this coming week for the benefit of interested students. Feel free to contact kathryn_streeter@fuller.edu with any questions.
Composition Workshop
How to develop a strong thesis statement, form coherent paragraphs, and use supporting evidence appropriately
Friday, November 7, 2008, from 1-3 p.m., in Payton 102
Advanced Composition Workshop
How to develop different kinds of thesis statements, transition deftly between paragraphs, smoothly integrate quoted material, and more!
Friday, November 14, 2008, from 1-3 p.m., in Payton 102
Grammar & Editing Workshop
How to fix common grammatical errors such as inconsistent verb tense, flawed sentence structure, and misplaced punctuation
Friday, November 21, 2008, from 1-3 p.m., in Payton 102
All workshops are FREE, and no RSVP is needed. A packet of helpful materials will be available at each workshop for $5.
Thank you for your help in getting the word out! Flyers will be available in classrooms this coming week for the benefit of interested students. Feel free to contact kathryn_streeter@fuller.edu with any questions.
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