Hello experts!

I’m trying to compute FBA, and would appreciate your advice on statistical matrices construction. We have three groups: typical population (T), disease population (D), and disease-related (Dr) population. My first version of design matrix is this:

1 1 0 0

1 0 1 0

1 0 0 1

Where the first column is intercept, the second is T group, the third is D group, and the fourth is Dr group. N lines for N subjects.

The contrast matrix for me to see the difference between groups:

(1) D > T 0 -1 1 0 (2) D < T 0 1 -1 0

(3) Dr > T 0 -1 0 1 (4) Dr < T 0 1 0 -1

Now comes the puzzle. Since fixelcfestats only accepts a single contrast, will I need to run the analysis twice? First, I will run (1) and (2) (supplying (1) and requesting -negative output as well), and then run (3) and (4) in the same manner? My question is whether this would be a correct way of running this type of analysis.

Thank you!

Olga