贴一个刚刚写的 (数据见附件)
use test,clear
gen msale=.
gen dev=.
forvalues i=2006(1)2011{
gen YEAR=year-`i'
reg sales YEAR if YEAR<6 & YEAR>0
predict p if YEAR<6 & YEAR>0,r
forvalues j=1(1)2{
sum p if stkcd==`j',de
dis "i=`i' j=`j'"
replace dev=r(sd) if stkcd==`j' & YEAR==5
sum sales if stkcd==`j' & YEAR<6 & YEAR>0 ,de
replace msale=r(mean) if stkcd==`j' & YEAR==5
}
drop YEAR p
}
dis "loop is over"
gen eu=dev/msale
欢迎讨论!!!
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