Hi-All.
I've already searched through the many postings on logistic regression and interaction effects and
did not see anything (that I recognized) related to this question.
I ran across a 2004 article by Norton et al, about a command in STATA, inteff, specifically
designed to correct for the nonlinear nature of the interaction effects in logistic regression. I am
interacting two dummy variables and in this article they argue the parameter estimates and the
direction of the effects, as well as the standard errors may be incorrect, if left unadjusted. For
two dummys, they argue the interaction effect is the discrete difference, and the standard errors
need to be calculated using the Delta method.
My question--first, is this a debatable topic? I would guess that it is, and there are differing
perspectives on whether or not this has to occur, or if the parameter estimates can be handled
from a theoretical standpoint like linear interaction effects.
Secondly, is it possible to calculate this using SPSS (v 16.0) or from the output from the model
estimated in SPSS? Is the discrete difference the same as added the value of the pararmeter of the
variable of interest + your interaction term with this variable, to get the value for the variable in
which you are interested?
Thanks.
Colleen
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