when to stratify or not to stratify an interaction when do you stratify a regression what is the difference between a interaction and a stratification of the sample when do we stratify in regression analysis when should you stratify an interaction in regression when to stratify an interaction vs. stratifying when should a regression be stratified vs. interaction when to stratify an interaction for a regression how to stratify in cox regression when to stratify a regression when do you stratify regression when to stratify a regression when do you use an interaction term in regression when should we stratify or include time term in regression when to stratify or exclude interaction in regression analysis when would you stratify for an interaction in a regression model when should the interaction be included when do we stratify regression analysis how to stratify a variable when to stratify an interaction