Merging Datasets faster

When merging two SAS data sets, many of us use one of these two methods to keep only the observations where both input data sets contribute: data test1; merge step1(in=a) step2(in=b); by district studentid; if a=1 and b=1; run; or data test1; merge step1(in=a) step2(in=b); by district studentid; if a and b; run; This method executes faster (and saves a few keystrokes): data test1; merge step1(in=a) step2(in=b); by district studentid; if a*b; run; This shortened version of the IF statement works since if either the variable a or b is false, the expression resolves to zero (false).