Date:         Fri, 23 Sep 2005 20:14:45 -0400
Reply-To:     Stephen Salbod <ssalbod@pace.edu>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Stephen Salbod <ssalbod@pace.edu>
Subject:      GLM Repeated with Categorical Covariates
Content-Type: text/plain; charset="us-ascii"

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