不好意思,错了一个地方:
set obs 1800
gen invest2=.
gen mvalue2=.
gen kstock2=.
gen newid=""
local k=1
forvalue i=1/200{
forvalues j=1/200{
if `i'!=`j'&year[`i']==year[`j']{
replace invest2[`k']=invest[`i']/invest[`j']
replace mvalue2[`k']=mvalue[`i']/mvalue[`j']
replace kstock2[`k']=kstock[`i']/kstock[`j']
replace newid="`i'by`j'"
dis `k++'
}
}
}