I have 2 datasets: treatment firms and control firms. I need to match these two datasets based on this equation: match error=∑_(k=1)^3〖((c_k^i-c_k^j)/(c_k^i+c_k^j ))〗^2  where i=treatment firm, j= control firm, and c_k is one of the three variables: log market capitalization, log volume, and price. I would like to match each test firm with a control firm (without replacement) based on the smallest match error from of the above equation.    Here is my sas code:    data control; set control; rename price_Mean=_price_Mean log_volume=_log_volume log_mrk_cap =_log_mrk_cap; k+1; run;   data want; if _n_ eq 1 then do; if 0 then set control; declare hash h(dataset:'control',multidata:'y'); h.definekey('control pool'); h.definedata('_price_Mean','_log_volume','_log_mrk_cap','k'); h.definedone(); end; call missing(of _all_); set treatment; n=0; min=9999999; rc=h.find(); do while(rc=0); merror=(((price_Mean-_price_Mean)/(price_Mean+_price_Mean))**2)+(((log_adv-_log_volume)/(log_volume+_log_volume))**2)+(((log_mrk_cap-_log_mrk_cap)/(log_mrk_cap+_log_mrk_cap))**2); if merror lt min then do;n=k;min=merror;end; rc=h.find_next(); end; rc=h.find(); do while(rc=0); if n=k then do;h.removedup();leave;end; rc=h.find_next(); end; run;   My problem that I'm having is that once I test the difference between the two groups by each criteria variable, they are significantly different. However, I know this could just be natural by the experiment I'm running but I want to make sure that it is not the result of the code.   Any comments or help would be appreciated. Thank you, Best, Donovan  ... View more