http://www.iangregory.com/Public ... /base/s/safesum.ado
*! version 3.0.3 28sep2004
program define safesum, rclass
* touched by jwh -- double saves
version 6.0, missing
syntax varlist(max=1) [fweight] [if]
qui summ `varlist' [`weight'`exp'] `if'
ret scalar sum = cond(r(N)==0 | r(N)==., 0, round(r(sum),1))
global S_1 `return(sum)' /* double save */
end
exit