ANOVA contrast coding for 4 groups.

#1
Hello,

I have four groups 1, 2, 3, and 4, and I'm trying to compare the average of 1 and 2 vs. group 3 and group 4 (note not the average of group 3 and 4).

Can someone help me with what my contrast coefficients should be?

Thanks in advance!
 

Miner

TS Contributor
#2
Are these two different contrasts? That is, you want to test (Group1 + Group2)/2 - Group3 = 0 AND also test (Group1 + Group2)/2 - Group4 = 0?