RE: st: help to understand syntax 'qui by study: gen last=_n==_N'

["b. water" <barleywater@hotmail.com>]

dear listers,

again, my apology if at some point in the near future, another two virutally 
identical postings appeared on the list. i tried to send this question 
earlier (x2) but seemed not to have appeared so i resorted to using reply 
instead and it seems to have worked for my other question, so here it is:

i am trying to understand one of the do-files application for stata. one of 
the lines read:

qui by study: gen last=_n==_N

my understanding so far: this is quietly, sort according to study, and as a 
result, to generate a variable 'last' fulfilling this condition _n==-N. 
although i have the output, i would like to know what in general does gen 
last=_n==_N do?

thank you,
bw

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