Re: Difference Score as a dependent variable

Posted by Andy W on Apr 17, 2014; 12:28pm
URL: http://spssx-discussion.165.s1.nabble.com/Difference-Score-as-a-dependent-variable-tp5725496p5725500.html

I agree with Art in that much more detail is needed to give useful advice. IMO general "how should I model this" questions aren't a great fit for a list-serve like this - it should be based on the consultation of domain experts in how you set up your study and your models. This is hard to give advice given the limited context of a list-serve. An email can't replace an academic advisor.

I don't feel too guilty throw pointing towards references. One of my favorites on the subject is

Allison, Paul D. 1990. Change scores as dependent variables in regression analysis. Sociological Methodology 20:93-114. Public PDF version.

The question comes up alot on the cross validated forum, here are a few questions relevant to the discussion (the second I have a quick run down of the Allison article):

 - Best practice when analysing pre-post treatment-control designs
 - Is it valid to include a baseline measure as control variable when testing the effect of an independent variable on change scores?

Given your goal I would say ignore the Edward's article. The fundamental problems with using change scores as independent variables are different. (I have a basic 100 word recap of the fundamental argument in the Edward's paper in this question on Cross Validated, Is it valid to use a difference score as an independent variable in a regression analysis.) The citation for the Edward's article for those interested is

Edwards, Jeffrey R. 2001. Ten difference score myths. Organizational Research Methods 4(3):265-287. Public PDF.