Mixed models Vs repeated measures ANOVA

[pran909]

Hi,

I have a dataset and our dependent variable is measured at five different time points. we want to know if there is a difference between the two groups that we are studying (control and experimental). We also want to know if the dependent variable response is changing over time.

I found from various resources that a mixed model approach would be appropriate for  my analysis. However, I would like to know what is the difference in the test statistic between the mixed models and repeated measures ANOVA (GLM)? do both these approaches use F-test for testing the significance effect? is there any difference in the way F-test statistic is computed between these two approaches?

Thanks.

[Swank, Paul R]

Two major differences: repeated measures has a limited covariance structure to work with, whereas mixed typically has more and therefore, more likely the right one. Second, repeated measures does listwise deletion for missing data, mixed does not. Mixed is maximum likelihood whereas repeated measures ANOVA uses set formulas. SO the F's could be different unless the structure of the covariance matrix is simple and there is no missing data.

Dr. Paul R. Swank,
Professor and Director of Research
Children's Learning Institute
University of Texas Health Science Center-Houston


-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of pran909
Sent: Friday, May 06, 2011 12:31 AM
To: [hidden email]
Subject: Mixed models Vs repeated measures ANOVA

Hi,

I have a dataset and our dependent variable is measured at five different
time points. we want to know if there is a difference between the two groups
that we are studying (control and experimental). We also want to know if the
dependent variable response is changing over time.

I found from various resources that a mixed model approach would be
appropriate for  my analysis. However, I would like to know what is the
difference in the test statistic between the mixed models and repeated
measures ANOVA (GLM)? do both these approaches use F-test for testing the
significance effect? is there any difference in the way F-test statistic is
computed between these two approaches?

Thanks.

--
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[Ryan]

It may be of interest to see an example of how F-statistics are
calculated within the context of a linear mixed model:

http://www.listserv.uga.edu/cgi-bin/wa?A2=ind1005&L=spssx-l&P=R34834

Shortly after posting the message above, I made a small clarification here:

http://www.listserv.uga.edu/cgi-bin/wa?A2=ind1005&L=spssx-l&P=R34947

HTH,

Ryan

On Sun, May 8, 2011 at 11:06 PM, Swank, Paul R <[hidden email]> wrote:

> Two major differences: repeated measures has a limited covariance structure to work with, whereas mixed typically has more and therefore, more likely the right one. Second, repeated measures does listwise deletion for missing data, mixed does not. Mixed is maximum likelihood whereas repeated measures ANOVA uses set formulas. SO the F's could be different unless the structure of the covariance matrix is simple and there is no missing data.
>
> Dr. Paul R. Swank,
> Professor and Director of Research
> Children's Learning Institute
> University of Texas Health Science Center-Houston
>
>
> -----Original Message-----
> From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of pran909
> Sent: Friday, May 06, 2011 12:31 AM
> To: [hidden email]
> Subject: Mixed models Vs repeated measures ANOVA
>
> Hi,
>
> I have a dataset and our dependent variable is measured at five different
> time points. we want to know if there is a difference between the two groups
> that we are studying (control and experimental). We also want to know if the
> dependent variable response is changing over time.
>
> I found from various resources that a mixed model approach would be
> appropriate for  my analysis. However, I would like to know what is the
> difference in the test statistic between the mixed models and repeated
> measures ANOVA (GLM)? do both these approaches use F-test for testing the
> significance effect? is there any difference in the way F-test statistic is
> computed between these two approaches?
>
> Thanks.
>
> --
> View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Mixed-models-Vs-repeated-measures-ANOVA-tp4375073p4375073.html
> Sent from the SPSSX Discussion mailing list archive at Nabble.com.
>
> =====================
> To manage your subscription to SPSSX-L, send a message to
> [hidden email] (not to SPSSX-L), with no body text except the
> command. To leave the list, send the command
> SIGNOFF SPSSX-L
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>
> =====================
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