%macro releff(data,npop,y,x) ;    
 proc corr data = &data outp = corrout noprint ;
  var &y &x ;
  run ;
 data corrout ; set corrout ;
  if _type_ = "CORR" and _name_ = "&y" ;
  rhohat = &x ;
  match = 'Y' ;
  keep rhohat match ;
 *proc print data = corrout ; run ;
 proc univariate data = &data noprint ;
  var &y &x ;
  output out = univout
    mean = mn&y mn&x  std = s&y s&x
    cv = cv&y cv&x n = nobs ;
  run ;
 data univout ; set univout ;
  match = 'Y' ;
 *proc print data = univout ; run ;
 data both ; merge univout corrout ; by match ;
  r = mn&y/mn&x ;
  popn = &npop ;
  relbias_ratio = (cv&x**2 -rhohat*cv&y*cv&x)*(popn-nobs)/(10000*popn*nobs) ;
  * divide by 10000 because SAS defines cv as 100(s/xbar) ;
  re_regr_ybar =  1/(1-rhohat**2) ;
  re_regr_ratio = (s&y**2 +(r*s&x)**2 -2*r*rhohat*s&y*s&x)/
                 (s&y**2*(1-rhohat**2)) ;
  re_regr_diff  = (s&y**2 +s&x**2 -2*rhohat*s&y*s&x)/
                 (s&y**2*(1-rhohat**2)) ;
 proc print data = both ; run ;
 %mend releff ;