Mixed linear model

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Mixed linear model

Carol
Hello
 
I ran a linear mixed model with a 5 continuous IV and one continuous DV. There are all measured at individual level (Level 1). But among the variables of control, there is one of them wich is measured at the organizational level (Level 2).
 
I started assessing the mean effects of these 5 IV on the DV. 2 of them are significant.
Then, I tested the interactions effects between fixed effects. 4 of them are significant.
I have two questions about these results: 
- First, is there any Excel spreadsheet wich can be used to plot these interaction effects?
- Second, as there are several significant interactions, how can I compare the results between each other?
 
Thank you very much in advance for your help
 
C.
 

 
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Re: Mixed linear model

Maguin, Eugene
Caroline,
 
Here are some references that you might find useful for graphing interactions. The list was given by Cam McIntosh on the semnet listserv. Of these, i think the Bauer and the Preacher references might be most helpful to you.
 
Gene Maguin
 
Garcia, R., & Kandemir, D. (2006). An illustration of modeling moderating variables in cross-national studies. International Marketing Review, 23(4), 371-389.
 
Bauer, D. J., & Curran, P. J. (2005). Probing interactions in fixed and multilevel regression: Inferential and graphical techniques. Multivariate Behavioral Research, 40(3), 373-400.
http://www.unc.edu/~dbauer/manuscripts/bauer-curran-MBR-2005.pdf

Hayes, A.F., & Matthes, J. (2009). Computational procedures for probing interactions in OLS and logistic regression: SPSS and SAS implementations. Behavior Research Methods, 41, 924-936. 
http://www.comm.ohio-state.edu/ahayes/MODPROBE.pdf

O'Connor, B.P. (1998). SIMPLE: All-in-one programs for exploring interactions in moderated multiple regression. Educational and Psychological Measurement, 58(5), 836-840.
https://people.ok.ubc.ca/brioconn/simple/simple.html

Whisman, M. A., & McClelland, G. H. (2005). Designing, testing, and interpreting interactions and moderator effects in family research. Journal of Family Psychology, 19, 111-120.

Dawson, J.F., & Richter, A.W. (2006). Probing three-way interactions in moderated multiple regression: development and application of a slope difference test. Journal of Applied Psychology, 91(4), 917-926.

Preacher, K. J., Curran, P. J., & Bauer, D. J. (2006). Computational tools for probing interaction effects in multiple linear regression, multilevel modeling, and latent curve analysis. Journal of Educational and Behavioral Statistics, 31(4), 437-
448.
http://www.unc.edu/~dbauer/manuscripts/preacher-curran-bauer-2006.pdf
http://www.people.ku.edu/~preacher/interact/index.html

Fletcher, T.D. (August 8, 2010). Quantitative Psychology Tools: Package ‘QuantPsyc’.
http://cran.r-project.org/web/packages/QuantPsyc/QuantPsyc.pdf
http://cran.r-project.org/web/packages/QuantPsyc/index.html

Armstrong, D. (May 19, 2010). Dave Armstrong’s Miscellaneous Functions: Package ‘DAMisc’, Version 1.0.
http://cran.r-project.org/web/packages/DAMisc/DAMisc.pdf
http://cran.r-project.org/web/packages/DAMisc/index.html
 


From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of CAROLINE TILLOU
Sent: Friday, June 10, 2011 3:59 PM
To: [hidden email]
Subject: Mixed linear model

Hello
 
I ran a linear mixed model with a 5 continuous IV and one continuous DV. There are all measured at individual level (Level 1). But among the variables of control, there is one of them wich is measured at the organizational level (Level 2).
 
I started assessing the mean effects of these 5 IV on the DV. 2 of them are significant.
Then, I tested the interactions effects between fixed effects. 4 of them are significant.
I have two questions about these results: 
- First, is there any Excel spreadsheet wich can be used to plot these interaction effects?
- Second, as there are several significant interactions, how can I compare the results between each other?
 
Thank you very much in advance for your help
 
C.
 

 
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Re: Mixed linear model

Salbod

Gene, thank you for making the references available on this list.  Steve

 

From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Gene Maguin
Sent: Monday, June 13, 2011 8:43 AM
To: [hidden email]
Subject: Re: Mixed linear model

 

Caroline,

 

Here are some references that you might find useful for graphing interactions. The list was given by Cam McIntosh on the semnet listserv. Of these, i think the Bauer and the Preacher references might be most helpful to you.

 

Gene Maguin

 

Garcia, R., & Kandemir, D. (2006). An illustration of modeling moderating variables in cross-national studies. International Marketing Review, 23(4), 371-389.

 

Bauer, D. J., & Curran, P. J. (2005). Probing interactions in fixed and multilevel regression: Inferential and graphical techniques. Multivariate Behavioral Research, 40(3), 373-400.

 

Hayes, A.F., & Matthes, J. (2009). Computational procedures for probing interactions in OLS and logistic regression: SPSS and SAS implementations. Behavior Research Methods, 41, 924-936. 

 

O'Connor, B.P. (1998). SIMPLE: All-in-one programs for exploring interactions in moderated multiple regression. Educational and Psychological Measurement, 58(5), 836-840.

 

Whisman, M. A., & McClelland, G. H. (2005). Designing, testing, and interpreting interactions and moderator effects in family research. Journal of Family Psychology, 19, 111-120.

 

Dawson, J.F., & Richter, A.W. (2006). Probing three-way interactions in moderated multiple regression: development and application of a slope difference test. Journal of Applied Psychology, 91(4), 917-926.

 

Preacher, K. J., Curran, P. J., & Bauer, D. J. (2006). Computational tools for probing interaction effects in multiple linear regression, multilevel modeling, and latent curve analysis. Journal of Educational and Behavioral Statistics, 31(4), 437-

448.

 

Fletcher, T.D. (August 8, 2010). Quantitative Psychology Tools: Package ‘QuantPsyc’.

 

Armstrong, D. (May 19, 2010). Dave Armstrong’s Miscellaneous Functions: Package ‘DAMisc’, Version 1.0.

 

 


From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of CAROLINE TILLOU
Sent: Friday, June 10, 2011 3:59 PM
To: [hidden email]
Subject: Mixed linear model

Hello

 

I ran a linear mixed model with a 5 continuous IV and one continuous DV. There are all measured at individual level (Level 1). But among the variables of control, there is one of them wich is measured at the organizational level (Level 2).

 

I started assessing the mean effects of these 5 IV on the DV. 2 of them are significant.

Then, I tested the interactions effects between fixed effects. 4 of them are significant.

I have two questions about these results: 

- First, is there any Excel spreadsheet wich can be used to plot these interaction effects?

- Second, as there are several significant interactions, how can I compare the results between each other?

 

Thank you very much in advance for your help

 

C.

 


 

 

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Re: Mixed linear model

jmdpulido
In reply to this post by Carol
Dear Caroline,

I program a different excel file to report results after running each multilevel analysis.

The steps I follow are the following:

- Before running the Mixed model, Grand-center all variables (substract them the mean of the whole population), so with all predictors equal to cero (the grand mean) the level 2 residual plus gamma 00 (the common intercept) will be the "mean" of your DV for a hypothetical "representative individual" belonging to each level-2 group.

- Then, using the coefficients of the regression and the interaction, calculate the effect of the changes in one IV (ceteris paribus) in the dependent variable for this "representative individual".

-  Recall that When you have interactions you have to take into account the beta coefficient of the principal variable and the interaction. If one of the interaction IV is a dummy (which is mostly the case), then it is useful to present 2 predicted value curves in the same graph (for both groups).

- Point estimates calculated this way for predicted values are pretty straightforward. Nevertheless, prediction intervals at a certain confident level are more difficult. You have to use the Var-Covar Matrix, in order to calculate the SE of the predicted value.

Mail me if you need a deeper explanation of the steps to follow.