I have a question regarding the Fit Model platform. Let's say that I am working with the Big Class data table. My Y variable is height and I have two effects in my model: age and sex.
I would like to know if the height difference between the groups 12 and 17 for M is significantly different from the height difference between the groups 12 and 17 for F. I think I can use the "Custom Test" feature but I am not sure of how to do that properly...
Thanks in advance!
Thanks this post is really helping indeed! In my example I have 3 treatments (A,B, C) and 2 Times (T0, T1) and I want to know if the difference between T1 and T0 is significantly different between the treatments.
If I understand correctly the first step of your post, in my situation the difference between T1 and T0 (T1-T0 = -T0-T0 = -2 T0) for the treatment A correspond to the following coefficients [0, -2, 0, 0,2,0,0]? I am not sure for the interaction term...
You can use contrasts instead of a custom test, although they are equivalent. I think that the contrast is easier to build and interpret. Set them up like this (mock up of data):
Hi @markbailey ,
Thanks for your answer! If I understand correctly, in your example you test that the difference between T0 and T1 is significantly different from 0 for each treatment. So if I want to know if the gap T0-T1 is different between two treatments, I need to subtract the corresponding columns?
But I've probably missed something because I get a warning: