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| From | Estrella Gomez <estrellastata@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: Different results with the same code |
| Date | Mon, 10 Feb 2014 11:24:47 +0100 |
I do the collapse by country and orig; and the variables I include in (firstnm) do not vary by country and orig, that's why I thougth that picking the first value in each case would be enough; because it should be equal to the rest of cases in that pair. Is not like that? Thanks, Estrella 2014-02-10 11:08 GMT+01:00 Nick Cox <njcoxstata@gmail.com>: > 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/ * * 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/