Re: REPEATED MIXED MODELS-post hoc tests/contrasts

Posted by Alexandra on Dec 29, 2014; 12:48pm
URL: http://spssx-discussion.165.s1.nabble.com/REPEATED-MIXED-MODELS-post-hoc-tests-contrasts-tp5728007p5728293.html

To answer to the other question the database is already in wide format. This is the output for the restructure.

SAVE OUTFILE='C:\Users\Alexandra\Desktop\ls\LSS.sav'
  /COMPRESSED.
VARSTOCASES
  /MAKE LSRT FROM LS_MEANRT1 LS_MEANRT2 LS_MEANRT3
  /INDEX=LISTLENGTH(3)
  /KEEP=COD_subiect Trait_anxiety age_group gender
  /NULL=KEEP.

Concerning the use of your previous suggested syntax (mixed ls by listlength with anxiety/fixed=listlength anxiety listlength*anxiety /repeated listlength | subject(id) covtype(cs), I changed it a bit in my previous e-mail from today but this would be the output from your syntax (the diff is in the cov type the fact that I used random intercept but in your syntax the repeated command mentioned LISTLENGTH-it's the same thing?)


MIXED LSRT BY LISTLENGTH WITH Trait_anxiety
  /CRITERIA=CIN(95) MXITER(100) MXSTEP(10) SCORING(1) SINGULAR(0.000000000001) HCONVERGE(0,
    ABSOLUTE) LCONVERGE(0, ABSOLUTE) PCONVERGE(0.000001, ABSOLUTE)
  /FIXED=LISTLENGTH Trait_anxiety LISTLENGTH*Trait_anxiety | SSTYPE(3)
  /METHOD=ML
  /PRINT=SOLUTION TESTCOV
  /REPEATED=LISTLENGTH | SUBJECT(COD_subiect) COVTYPE(CS).

  Resulting output (without gender):


Parameter                                         b    SE          t      Sig.
                               
Intercept                                   129,3 300,96 ,43      ,66
[LISTLENGTH=1]                             455,5 307,3 1,48       ,14
[LISTLENGTH=2]                            577,5 307,4 1,87        ,06
[LISTLENGTH=3]                                 0a      0          .         .
Trait_anxiety                            44,28      8,71 5,08      ,000
[LISTLENGTH=1] * Trait_anxiety   -27,75  8,89   -3,12      ,002
[LISTLENGTH=2] * Trait_anxiety   -25,07  8,90        -2,81      ,005
[LISTLENGTH=3] * Trait_anxiety         0a       0   .           .
a. This parameter is set to zero because it is redundant.
b. Dependent Variable: LSRT.

I have the same question: how can I interpret this interaction? should I use dummy codes for three level within factor interaction (Listlength). Or what does the zero parameter from listlength 3 mean?