Case-crossover study: conditional logistic regression

[RonD McDowell]

I have data from a case-crossover study. Prescription data on whether individuals have a given prescription at time 1 (yes/no) and time 2 (yes/no). I am interested in a within person analysis.
I also know individual's gender, and it is the effect associated with gender on outcome prescription that I wish to estimate. I planned to analyse this via a conditional logistic regression model (clogit), however gender is not something that changes within individuals between times 1 and 2, but rather differs between individuals. Does anyone have a suggestion as to where to start on the analysis? Any pointers would be gratefully appreciated.Thank you.

[Rich Goldstein]

why not have time2 as the outcome and time1 and gender as covariates?

I am not clear about what you mean by "a within person analysis" so the above might not be what you want

[Steve Samuels]

It would be easy to answer the question in your terms if you would provide an extract of your data, using the downloadable command DATAEX, as requested in FAQ 12 , or the equivalent. Be sure to put everything between CODE delimiters.

[Mike Lacy]

Effects of individual-level variables are not estimable in case-crossover designs, because, as you note, there is no variability in gender within individual. You can, however, estimate interactions of individual-level variables with time.

[RonD McDowell]

Thanks for your input, I have been able to work through what I'm looking for using conditional logistic regression. As an aside, I don't see an option for doing multilevel conditional logistic regression in stata, where I can put in cluster variables using random effects, though I can add vce(cluster x) to my clogit command. Is this correct?