I've been running proc psmatch for an analysis, using 1:1 nearest neighbor matching on propensity scores calculated from proc logistic. I did not include the WEIGHT=ATT option in the ASSESS statement to my code. Are the matching results still valid? Which weighting scheme is proc psmatch using as a default? I do see in the output dataset of matched records _MATCHWGT_=1 for every record. proc psmatch data=logistic_output;
class class age gender;
psdata ps=ps treatvar=class(treated='Treatment');
match method=greedy(k=1) exact=(age gender) caliper=0.25;
output out(obs=match)=psm_results;
run;
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