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| From | Nick Cox <njcoxstata@gmail.com> |
| To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
| Subject | Re: st: Different results with the same code |
| Date | Mon, 10 Feb 2014 10:08:00 +0000 |
Wrong way round: -collapse- reports (firstnm) as it finds them; it's the sorting that includes some arbitrariness. But evidently you have different values on variables for which you select (firstnm), so why do you want to pick the first non-missing and what sort order do you want? Nick njcoxstata@gmail.com On 10 February 2014 09:59, Estrella Gomez <estrellastata@gmail.com> wrote: > 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 <njcoxstata@gmail.com>: >> 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 >> njcoxstata@gmail.com >> >> >> On 10 February 2014 09:07, Estrella Gomez <estrellastata@gmail.com> 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 >>> * >>> * For searches and help try: >>> * http://www.stata.com/help.cgi?search >>> * http://www.stata.com/support/faqs/resources/statalist-faq/ >>> * http://www.ats.ucla.edu/stat/stata/ >> * >> * For searches and help try: >> * http://www.stata.com/help.cgi?search >> * http://www.stata.com/support/faqs/resources/statalist-faq/ >> * http://www.ats.ucla.edu/stat/stata/ > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/