Hi Alfonso, 
I have a follow up question that is related to the posts above. I have a design where I am combining data from 3 studies. 2 of the studies have subject at 2 time points, while the third study only has one time point. In addition, some time point 1 and time point 2 data is missing from one study. Can I use the same strategy that you described here, even if some subjects only have time point 1 or time point 2 data?
Thanks so much!
Tamara