st: More efficient way to calculate formula

[Nikolaos Kanellopoulos <nkkanel@yahoo.gr>]

Dear all,

I have the sales of some firms for various products by consumer and I want to estimate the following: Total sales of firm i of product j / (Number of consumers that contribute 60% of sales + 1).

My thought is the following:clear
webuse productivity

//year will be firm i
//region will be the product j
//state will be the consumer; can appear multiple times, ie buy from many firms
//gsp will be the sales

sort year region state gsp

bys year region (gsp): cumul gsp, gen(v1)
bys year region (gsp): cumul gsp, gen(v2) f

gen v5=floor(10*v1)
recode v5 (7/10=6) //This is done in case 60% is not observed
gen temp=.
egen tot_p=total(gsp) , by(year region)
bys year region v5 (gsp) : gen i=_n

bys year region :replace temp = tot_p/(v2+1) if v5==6 & i==1 

Is there a better-more efficient way to do this because I have quite a lot of consumers and the above code takes too long.

Thanks in advance
Nikos

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