I have 2 groups of 15 subjects for a VBM study and made the preprocessing.
Now I'd like to do the stats and I'm a little bit lost to covariate with age and sex.
How to put the vectors for sex (-1; 1?) and age (difference with the mean?)
Is the order of the value the order of the subjects successively in the 2 groups (the 16th value is the one for the 1st subject of the 2d group for example)?
Thank you in advance for your response.