Hello,
Just a small follow up on this question to clarify:
1) In general terms if we have an ANOVA design with 3 groups, want to test for any possible difference between the groups and we want to control the analysis for different covariates (sex, age, etc) we just need to add those collumns in front of the design as such:
1 0 0 -1 -2.4 1.3
1 0 0 1 1.1 0.1
0 1 0 1 0.3 -0.2
0 1 0 -1 -3.2 -2.1
0 0 1 1 -1.2 -3.1
0 0 1 1 4.1 4.5

and then use with F-contrast:
[1 1 1 0 0 0] 

2) I explored NBS code a little bit and if I understood correctly what NBS does is a regression using the co-variables (at 0 in the contrast) to obtain the residuals and then use those residuals to do the ANOVA, is this correct?

3) If I want to explore linear effects (g1>g2>g3), I should replace the design with a more GLM kind format?
Such as
1 1 -1 -2.4 1.3
1 1 1 1.1 0.1
1 2 1 0.3 -0.2
1 2 -1 3.2 -2.1
1 3 1 -1.2 -3.1
1 3 1 4.1 4.5

and then use t-test contrast [ 0 -1 0 0 0] to test.

Best regards, Ricardo