[first question, apologies any ambiguities/violations of question conventions]
Within a dataset, I have a continuous variable of interest (X), and I want to test for differences in variance of that variable between subgroups of interest. For example: does the variance of X differ between males and females?
After reviewing literature (see Lim & Loh, 1996), I decided to use the bootstrap-version of the Brown-Forsythe modified Levene test.
My dataset combines data from several different studies with different methods, ascertainment strategies, etc., so I first tested for variance differences as a function of study. I found a significant effect of study.
On the basis of that finding, I would like to test for significant differences in X across subgroups while controlling for the effect of study. Is there a natural, commonly used way to do this within the context of the Levene test?