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Re: st: Keep observations in 1/100 by country and year


From   Estrella Gomez <estrellastata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Keep observations in 1/100 by country and year
Date   Tue, 7 May 2013 17:24:09 +0200

Thanks!

2013/5/7 Ryan Stevens <stevrl7@gmail.com>:
> The gsort command is correct, but you are resorting your dataset again
> when using bysort. Instead a simple by command would work. Using
> Stata's built in observation macro, _n, should do the trick:
>
> gsort country year -tot_sales
> gen top100 = 0
> by country year: replace top100 = 1 if _n <= 100
>
> Ryan
>
> On Tue, May 7, 2013 at 10:49 AM, Estrella Gomez <estrellastata@gmail.com> wrote:
>>
>> Hi, statalisters
>>
>> I have a dataset with songs by year and country. I would like to keep
>> only the top 100 songs for each country each year (there are 18
>> countries and 6 years). I have tried the following:
>>
>> gsort country year -tot_sales
>> *because I want the songs with higher number of sales
>>
>> gen top100=0
>> bysort country year: replace top100=1 in 1/100
>> *to generate a dummy that takes value one for the top 100 songs, so I
>> can drop observations that equals zero
>>
>> However, Stata says that it's not possible to combine "by" with "in"
>>
>> Any idea?
>> Thanks a lot,
>> Estrella
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