Hello everyone.

I am trying to run this loop. I need to get two subsamples of frequent and occasional acquirers. the first one represents firms that made at least 2 deals over a 3 year window and the second one firms that made at least 5 deals over a 3 year window. My sample period is 1990-2011.

This is what I have so far but STATA gives me error "variable count already defined" and I can't figure out how to solve this.

Does anyone have any advice?

Thanks in advance!

Code:
forval year = 1990(1)2011{
keep if year >= `year'
keep if year <= `year' + 3
gen count =.
replace count = 1
collapse (sum) count (first) year, by(AcquirorCUSIP)
keep if count > 2
if `year' > 1990{
append using frequent_acq.dta
}
save frequent_acq.dta, replace
}