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| From | "Meulemann Max" <mmeulemann@ethz.ch> |
| To | "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu> |
| Subject | AW: AW: st: prgen option quadratic term |
| Date | Wed, 7 Nov 2012 11:29:34 +0000 |
I had hoped that was taken care of by the margins command ologit y capitagdp c.capitagdp#c.capitagdp i.socioecovars margins, at(c_capitagdp=(0.5(0.5)9)) atmeans predict(outcome(4)) marginsplot which looked the same as ologit y c_logcapitagdp c_logcapitagdpsquared $socioecovars oprobpr c_logcapitagdp, levels(c_logcapitagdpsquared=c_logcapitagdp^2) cat(4) newobs(100) In the linear model that graph is downward slooping and in the quadratic model it is downward slooping and then turning up ________________________________________ Von: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu]" im Auftrag von "Nick Cox [njcoxstata@gmail.com] Gesendet: Mittwoch, 7. November 2012 11:42 An: statalist@hsphsun2.harvard.edu Betreff: Re: AW: st: prgen option quadratic term When you are fitting a linear term and a quadratic term, the two act together. It's their combined effect that you need to interpret. This is usually easier with a graph. For example, one negative coefficient and one positive coefficient mean a turning point somewhere, but not necessarily within the range of the data. Nick On Wed, Nov 7, 2012 at 10:35 AM, Meulemann Max <mmeulemann@ethz.ch> wrote: > thx, the margins and marginsplot function helped a lot. > > Anyways anybody got a idea how I am to interpret my data here: I find a negativ linear term for capitagdp, but if i include a quadratic gdp term, that one turns out to be positiv and significant with a lrtest. > Plotting with marginsplot tells me then that for the linear model the probability to agree with a certain issue decreases whereas it increases with capitagdp for the quadratic model, keeping fixed my other covariates > ________________________________________ > Von: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu]" im Auftrag von "Maarten Buis [maartenlbuis@gmail.com] > Gesendet: Dienstag, 6. November 2012 17:10 > An: statalist@hsphsun2.harvard.edu > Betreff: Re: AW: st: prgen option quadratic term > > Also see: <http://www.maartenbuis.nl/wp/inter_quadr/inter_quadr.html> > > -- Maarten > > On Tue, Nov 6, 2012 at 4:26 PM, Richard Goldstein > <richgold@ix.netcom.com> wrote: >> I am not familiar with prgen >> >> sounds like you want the -margins- command? >> >> On 11/6/12 10:24 AM, Meulemann Max wrote: >>> I d like to get the predicted probabilites as my contionus predicator changes keeping fixed the other ones as it is done in -prgen- only with a quadratic term of that predicator. I do not just want the predicted probabilites. >>> >>> ________________________________________ >>> Von: owner-statalist@hsphsun2.harvard.edu [owner-statalist@hsphsun2.harvard.edu]" im Auftrag von "Richard Goldstein [richgold@ix.netcom.com] >>> Gesendet: Dienstag, 6. November 2012 16:10 >>> An: statalist@hsphsun2.harvard.edu >>> Betreff: Re: st: prgen option quadratic term >>> >>> I don't understand; why don't you start by telling us what is wrong with >>> just using -predict- after your -ologit-? for help on this, start with >>> -h ologit-, then click on "also see" and click on "ologit postestimation" >>> >>> Rich >>> >>> On 11/6/12 10:07 AM, Meulemann Max wrote: >>>> I would like to calculate predicted probabilities in an ordinal model, ologit or oprobit. I am using a continous quadratic term, which makes calculating the predicted probablities more cumbesome. I am using stata 12 >>>> >>>> I found an old entry in the statalist archive that proposed oprobpr which does work. I was wondering if another package has been written since 2005. >>>> >>>> oprobpr does work, but some of it its features are a bit irritating like how it saves the predicted probailites in another dataset and so on. The nicest way would be to change prgen and its familiar option in a way that the same feature that works for oprobpr would work for prgen. >>>> >>>> the level options allows oproppr to vary an otherwise fixed covariate with a squared term, which is not possible for the x option of prgen. >>>> * * 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/