How to do 2x2, between and within, analysis?

Discussion in 'SPSS' started by Jim Kroger, Nov 18, 2004.

  1. Jim Kroger

    Jim Kroger Guest

    Hi. I've always done within subjects designs, and now need to analyze
    a design with one dependent variable measured across two groups.
    Musicians and non-musicians were each given both a spatil reasoning
    test and a verbal reasoning test. The design sort of looks like the
    following, in which musical ability is a between subjects factor,
    and reasoning is a within subjects factor.


    musical abillity
    musician nonmusician


    spatial
    reasoning
    verbal


    I'm having trouble figuring out how arrange the data, and how to
    do the test. Is it the univariate GLM? I presume reasoning is the
    random factor and musical ability if the fixed factor. But I'm unsure
    how to handle the dependent variable? Does it appear as a separate
    column in the data sheet?

    Thanks in advance for any help or pointers to info.

    Jim
     
    Jim Kroger, Nov 18, 2004
    #1
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  2. Jim Kroger

    Bruce Weaver Guest

    Your file should have one row per person with (at least) these 3
    columns: One to code musician v non-musician; and one for each
    reasoning score.
    See above.
    Repeated measures ANOVA can used when you measure the *same* variable
    two or more times for each person. It is not meant for the case where
    measure two or more *different* variables for each person. In that
    case, you might use MANOVA.

    So, are spatial and verbal reasoning two measures of the same thing? Or
    are they two different things? (FWIW, I think they are two different
    things.)

    To get SPSS to do the work...

    For repeated measures: Analyze/GLM/Repeated measures
    For MANOVA: Analyze/GLM/Multivariate

    To save the syntax, exit the dialogs via <Paste> rather than <Okay>.

    The MANOVA will give you so-called univariate tests, which for your data
    would be equivalent to two unpaired t-tests, one for each type of
    reasoning. Given that you have only two measures, it might be simpler
    to just go with these two unpaired t-tests.
     
    Bruce Weaver, Nov 18, 2004
    #2
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  3. Jim Kroger

    Jim Kroger Guest

    Bruce, thank you so much for your help. I tried it, and it all works
    great with what the command interface wanted, and the analysis looks
    good.

    Jim
     
    Jim Kroger, Nov 19, 2004
    #3
  4. Jim Kroger

    Bruce Weaver Guest

    Grand. Just out of curiousity, did you decide to treat the two
    reasoning scores as repeated measures of the same variable, or as two
    different variables?
     
    Bruce Weaver, Nov 19, 2004
    #4
  5. Jim Kroger

    Jim Kroger Guest

    Hi Bruce. Well, we decided to treat it as two levels of the variable
    reasoning. You've probably heard of the Mozart effect, which improves
    spatial reasoning. We're comparing its effect on verbal reasoning. So
    the critical issue is comparison of spatial to verbal reasoning, so it
    seemed intuitive to treat them as levels of a variable.

    Thanks again for your help...
    Jim
     
    Jim Kroger, Nov 20, 2004
    #5
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