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Re: st: Different results with the same code


From   Estrella Gomez <[email protected]>
To   [email protected]
Subject   Re: st: Different results with the same code
Date   Mon, 10 Feb 2014 10:59:11 +0100

Hi, Nick

I have tried sorting just before the collapse and it happens the same
thing. Does (firstnm) use random values each time then?

Thank you,
Estrella

2014-02-10 10:41 GMT+01:00 Nick Cox <[email protected]>:
> Contrary to your claim, I would point at this:
>
> Which values are (firstnm) is likely to depend on the exact sort order
> of your data and you are sorting before you -collapse-.
>
> As Phil Schumm often explains, you could get consistent results by
> insisting on stable sorting, but that would be hiding a bug. There's
> evidently some arbitrariness that is better fixed directly.
> Nick
> [email protected]
>
>
> On 10 February 2014 09:07, Estrella Gomez <[email protected]> wrote:
>> Dear Statalisters
>>
>> I am running a code and I have realized that every time I run it the
>> results (the coefficients and the standard errors) are different. This
>> is the code:
>>
>> clear all
>> use "itunes_grav_song", clear
>> sort id country orig
>>
>> egen  nb_id=tag(id)
>> bysort orig: egen nr_orig=sum(nb_id)
>> bysort orig country: egen nr_dest=sum(available)
>> gen avail_share=(nr_dest/nr_orig)
>> collapse (count) nr_songs=id (firstnm) contig comlang ldist
>> avail_share, by(country orig)
>> encode country, gen(d_id)
>> encode orig, gen(o_id)
>> gen home=country==orig
>>
>> reg avail_share ldist comlang home i.d_id i.o_id
>>
>>
>> I have checked and after the collapse I obtain every time the same
>> dataset, so I don't know what can be the reason
>>
>> Thanks for any help!
>> Estrella
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