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LucyB
Obsidian | Level 7

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?

4 REPLIES 4
Reeza
Super User

I think you need a PROC ANOVA not a T-Test. 

 

 

LucyB
Obsidian | Level 7

So would be outcome variable be the difference? And my independent would be gender, but do I need to adjust for baseline (pre) scores as well?

Reeza
Super User

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

 

 

 

Reeza
Super User

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. 

 

 

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