Hi,
I have three variables, x, y, and z. x and y are categorical variables, x takes 0 and 1, but y takes 1, 2, and 3.

I want to do a t-test on z as follows:

(z if x==0 and y==1) == (z if x==0 and y==2)
(z if x==0 and y==3) == (z if x==0 and y==2)

(z if x==1 and y==1) == (z if x==1 and y==2)
(z if x==1 and y==3) == (z if x==1 and y==2)

How can I conduct such tests? I'd appreciate your help. Thanks,