st: Errors in egen, total()

["Mike Kim" <kalisperos@gmail.com>]

Hello all,

I used "egen total()" to create "cumrev" like the following, but if there is 
only one week per title, total gives a slightly lower number than the 
original number in some cases (1 or 2 lower). Any idea about why it produces 
different numbers?

bys title week: egen cumrev=total(rev)

title   week    rev                 cumrev
A       707     28536717     28536716
A       708     10                   30
A       708     20                   30
B        801    .....
......

Thank you,
Mike. 

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