I did some t-test (two-tailed) and keeps geting weird degrees of freedom.
I have some pairs of vectors, all of size = [1 144], so n=144 observations for each group
ttest gave me the expected df (142) for some tests, but I also got 139 in another one, and even... 124 in an other one.
What is going on ? Why is the degree of freedom not 142 in all those tests ?