Date: Fri, 21 Apr 2006 09:46:07 -0500
Reply-To: "Reutter, Alex" <areutter@spss.com>
Sender: "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From: "Reutter, Alex" <areutter@spss.com>
Subject: Re: repeated measures and varying covariates
Content-Type: text/plain; charset="us-ascii"
Since the data structure required by Linear Mixed Models puts the repeated measurements in the cases rather than the variables, you simply specify different values of the covariate for different cases.
See Help>Case Studies, Advanced Models Option>Linear Mixed Models>Using Linear Mixed Models to Analyze Repeated Measurements for detailed instructions on converting data set up for MANOVA/GLM to the structure required by MIXED.
Cheers,
Alex
> -----Original Message-----
> From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
> Paul McGeoghan
> Sent: Friday, April 21, 2006 5:59 AM
> To: SPSSX-L@LISTSERV.UGA.EDU
> Subject: repeated measures and varying covariates
>
> Hi,
>
> I have 1 varying covariate with three levels and one repeated measure with
> 3 levels.
> The syntax I have at the moment in SPSS is:
>
> MANOVA rs1 TO rs3 WITH sf1 TO sf3
> /WSFACTORS = SUMTYPE(3).
>
> which gives me output at the bottom of this email. The last part of the
> output which is the Tests of Within-Subjects effects is telling me that
> there is a significant overall SUMTYPE effect adjusted for the covariate
> while the REGRESSION tells me that there is no linear relationship between
> the dependent variable and the covariate?
>
> Is that correct?
>
> I have also looked at Linear Mixed Models as a possibility in SPSS but it
> is much more complex and the example in SPSS 13 Advanced Statistical
> Procedures Companion on page 239 for repeated measures is only for a
> constant covariate. How do I specify a varying covariate in Linear Mixed
> Models.
>
> Paul
>
>
>
> * * * * * A n a l y s i s o f V a r i a n c e -- design 1 * * * * *
> *
>
> Tests of Between-Subjects Effects.
>
> Tests of Significance for T1 using UNIQUE sums of squares
> Source of Variation SS DF MS F Sig of F
>
> WITHIN CELLS 34.74 10 3.47
> REGRESSION 34.01 1 34.01 9.79 .011
> CONSTANT 12.27 1 12.27 3.53 .090
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> Regression analysis for WITHIN CELLS error term
> --- Individual Univariate .9500 confidence intervals
> Dependent variable .. T1
>
> COVARIATE B Beta Std. Err. t-Value Sig. of t
>
> T4 .01626 .70338 .005 3.129 .011
>
> COVARIATE Lower -95% CL- Upper
>
> T4 .005 .028
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>
>
>
> * * * * * * A n a l y s i s o f V a r i a n c e -- design 1 * * * *
> *
> *
>
> Tests involving 'SUMTYPE' Within-Subject Effect.
>
> AVERAGED Tests of Significance for rs using UNIQUE sums of squares
> Source of Variation SS DF MS F Sig of F
>
> WITHIN CELLS 89.83 21 4.28
> REGRESSION .01 1 .01 .00 .973
> SUMTYPE 55.62 2 27.81 6.50 .006
>
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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