Re: Difference Score as a dependent variable
Posted by
Art Kendall on
Apr 17, 2014; 11:40am
URL: http://spssx-discussion.165.s1.nabble.com/Difference-Score-as-a-dependent-variable-tp5725496p5725499.html
Does the design include
a pre-test and a post-test? Are you looking as a difference in
change question?
If so one approach is to use a stepped (NOT stepwise) ordinary
regression approach with the pre-test as a predictor, so that
the DV on the second step is effectively the residual.
Another is a repeated measures ANOVA. (ANCOVA would not allow you
to test the interaction of the pre-test with the other
predictors.)
You can use many instances of the general linear model -- ordinary
regression, ANOVA, etc. depending on what your other predictors
are. List members would need more details about your design,
number of cases, etc. to be more specific.
I don't have the citations at hand, but someone on this list most
likely does.
Art Kendall
Social Research Consultants
On 4/16/2014 7:11 PM, Laura2014 [via SPSSX Discussion] wrote:
Hi,
I am working on a study in which we test the effect of a
behavioral variable X on a difference score variable Y. The
difference score is build out of two distinct factors (Ya - Yb).
However I know scholars such as Edwards strongly recommend to not
just compute in SPPS the dependent variable as Ya-Yb.
I found several alternatives for using difference scores such as
polynomial regression. But from my understanding, techniques such
as polynomial regression can only be used when the difference
score is your independent variable.
Besides testing the effect of X on Ya and Yb separatly, I was
wondering whether anyone has other suggestions to address the
difference score? (which can be performed in SPSS or AMOS)?
Thanks!
Laura
Art Kendall
Social Research Consultants