03-09-2017 04:36 PM
I have pre/post data for one group - outcome is a score. I am interested to see if the scores vary by a covariate like gender. If I use the by command in the ttest procedure, it does not give me a significant p value for differences by gender. how can i go about doing this?
03-09-2017 09:33 PM
Pre-calculate the differences and test if the difference is different between the groups and not equal to 0.
ie Mean from Group A = Mean from Group B = Mean from Group = 0
where mean = post-pre score
03-09-2017 05:11 PM
Also, BY statements splits an analysis for each group. It's the equivalent of doing some repeatedly for each group but they're considered individually. Analyses do not cross between BY groups.