Date:         Fri, 23 Sep 2005 23:09:34 -0400
Reply-To:     Lisa Stickney <Lts1@enter.net>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Lisa Stickney <Lts1@enter.net>
Subject:      Re: GLM Repeated with Categorical Covariates
Comments: To: Stephen Salbod <ssalbod@pace.edu>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=original

Hi Stephen,

       There may be a problem with your code.  If you have any missing data,
you've just relegated it to ethnic4 (the drop out category).  When you run
through your COMPUTEs for ethnic 1 to 3, teh missing data along with all you
other cases got a value of 0.  Then in the If statement the valid data for
that ethnicity got a value of 1 on that pass, but you never correct the
missing data.  You might want to try this after the COMPUTE statements:

IF MISSING(ethnic) ethnic1 = $SYSMIS.
IF MISSING(ethnic) ethnic2 = $SYSMIS.
IF MISSING(ethnic) ethnic3 = $SYSMIS.
IF MISSING(ethnic) ethnic4 = $SYSMIS.

    Good luck.

        Lisa

Lisa T. Stickney
Ph.D. Student
The Fox School of Business
     and Management
Temple University


----- Original Message -----
From: "Stephen Salbod" <ssalbod@pace.edu>
Newsgroups: bit.listserv.spssx-l
To: <SPSSX-L@LISTSERV.UGA.EDU>
Sent: Friday, September 23, 2005 8:14 PM
Subject: GLM Repeated with Categorical Covariates


>A Friday question: I want to us ethnicity (4 levels) as a covariate in an
> ANCOVA procedure. I think the code is correct, but since I've never worked
> with a set, as covariate, I'm a little concerned. The Syntax Guide had
> little to say on this issue (see GLM: Repeated Measures, 726-734).
>
>
>
> COMPUTE Ethnic1 = 0.
>
> COMPUTE Ethnic2 = 0.
>
> COMPUTE Ethnic3 = 0.
>
>
>
> DO IF (Ethnic EQ 1).
>
> - COMPUTE Ethnic1 = 1.
>
> ELSE IF (Ethnic EQ 2).
>
> - COMPUTE Ethnic2 = 1.
>
> ELSE IF (Ethnic EQ 3).
>
> - COMPUTE Ethnic3 = 1.
>
> END IF.
>
>
>
> GLM
>
>  pretest posttest BY group  WITH ethnic1 ethnic2 ethnic3
>
>  /WSFACTOR = time 2
>
>  /METHOD = SSTYPE(3)
>
>  /EMMEANS = TABLES(group*time) WITH(ethnic1=MEAN ethnic2=MEAN
> ethnic3=MEAN)
>
>  /CRITERIA = ALPHA(.05)
>
>  /WSDESIGN = time
>
>  /DESIGN = ethnic1 ethnic2 ethnic3 group .
>
>
>
> Any suggestions will be most welcome.
>
>
>
> TIA.
>
>
>
> Stephen Salbod, Pace University, NYC
>