Dear SDM experts,

I am using SDM 6.21 and want to enter a study to my meta-analysis where I have difficulties deciding with contrast to select. So I tried to combine two contrasts by averaging them. I have read the previous posts in the forum about this, and tried doing the following. It does work and gives results (all looks fine), but could you tell me if it is ok to do so?

First, I entered the two different contrast like two different studies in my SDM table. Then I ran SDM preprocessing. Then I average the *_lower.nii.gz and the *_upper.nii.gz files, as well as the t_*_lower.nii.gz and t_*_upper.nii.gz files, for the two different contrasts ("studies"). For that I used the combine images button in SDM. Then I modified the sdm_table, sdm_maps, sdmpsi_params, etc. files, and exchanged the two old studies (unaveraged) with the one new study (average). Then I ran the further analyses in SDM (e.g. mean analysis), but did not repeat preprocessing anymore.

Does this makes sense / is ok to do?

Many thanks!
Matthias