# Conditional logistic regression- effect of modifiers

#### AlinaVo

##### New Member
Hi everybody,
I am new here in this forum.

I am studying the effect of air pollution (PM) on health outcomes, and the characteristics that might modify this effect, using the case crossover analysis. This analysis followed a case crossover procedure where each subject with event contributes information as a case and as matched control during nonevents times therefore, i use the the conditional logistic regression for the analysis.

When I examining the interaction term of gender (0=Male and 1=Female) ,the independent variables in the model are: PM+PM*Gender.

The question is: how can i see 3 coefficients ( 1- general effect, 2- for Females 3 for Males)

I am confused because, if the Males is the reference, then the Males estimate should be the same as the overall estimate?

Thank yous very much for your efforts,
Alina