Hi, Thanks for the input on survey weights, it was very helpful. What I still don't understand is how to turn MatchIt output into a single value for ATT. I re-read the manual and showed it to several experienced quantitative research faculty at my university over this past week, but nobody could even remotely figure out how to interpret the output that MatchIt produces. I understand the concept behind ATT but am having trouble with the correct practical application. Could someone please provide the specific formulas and steps needed to convert MatchIt output for ATT (as provided in an example below) into an actual ATT value? Sorry if this is a mundane request but since even seasoned faculty couldn't help me out there might be a broader need for a basic stepwise tutorial for turning MatchIt output into a single value for ATT. This way, less experienced researchers like myself could take better advantage of this great piece of software. Many thanks in advance, Sinan MatchIt ATT output example: Mean Values of Observed Data (n = 264) (Intercept)=1.0000 sex=1.4470 race=4.6780 fcomp=1.6515 ses=-0.1496 lang=0.8333 prog=1.8409 urban=1.8788 control=1.2197 math=46.7506 reading=46.1787 expect=4.4356 atw=11.1742 Pooled Expected Values: E(Y|X) mean sd 2.5% 97.5% 3.9676 0.5416 2.9361 5.0558 Pooled Average Treatment Effect for the Treated: Y - EV mean sd 2.5% 97.5% 0.26723 0.07029 0.12872 0.39879 -- MatchIt mailing list served by Harvard-MIT Data Center List Address: matchit(a)lists.gking.harvard.edu Subscribe/Unsubscribe: http://lists.gking.harvard.edu/?info=matchit MatchIt Software and Documentation: http://gking.harvard.edu/matchit/ Browse/Search List Archive: http://lists.hmdc.harvard.edu/lists/matchit/