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From | "Vassilopoulos Achilleas" <vassilopoulos.statalist@gmail.com> |
To | <statalist@hsphsun2.harvard.edu> |
Subject | RE: st: RE: condivreg/Multicollinearity |
Date | Fri, 10 Sep 2010 01:43:59 +0300 |
Then I guess that your collinearity doesn't arise only from the first step but also from the next steps of the -ivregress-. -ivregress- uses three tests for collinearity, one after the other, before the estimation. What you can do is to replicate these tests by hand and save the non-collinear variables of every step so you can use them later. See below : _rmdcoll ENDOGENOUS INCLUDED-EXOGENOUS, forcedrop //checks for collinearity between endogenous vars and included exogenous// global first `r(varlist)' //This global contains the set of non-collinear included vars// _rmcoll dummy1-dummy500 //checks for collinearity among instruments// global inst_first `r(varlist)' //this global contains the dummies that are not collinear between themselves// _rmcoll2list, alist($first) blist($inst_first) //checks for collinearity among the endogenous and all exogenous vars and further drops instruments until a linearly independent set is obtained // global inst `r(blist)' //this global contains the final set of non-collinear instruments// I guess all you need from this point on are the globals $inst and $first Hope this helps, _____________ - _______________ Achilleas Vassilopoulos Agricultural University of Athens, Dept. of Agricultural Economics and Rural Development, Lab. of Political Economy and European Integration. Iera Odos 75, 11855, Athens, Greece Tel: (+30) 210-5294726 Fax: (+30) 210-5294786 email : avassilopoulos.aua@gmail.com -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of richard boylan Sent: 09 September, 2010 17:12 To: statalist@hsphsun2.harvard.edu Subject: Re: st: RE: condivreg/Multicollinearity That does not work, I still get the same error message after "condivreg." ivreg eliminates many more dummy variable than only estimating the first stage with reg. So, ideally, I would want to follow the same procedure you described using ivreg if I knew how to access the first stage coefficients. On Thu, Sep 9, 2010 at 2:53 AM, Vassilopoulos Achilleas <vassilopoulos.statalist@gmail.com> wrote: > If your dummies are collinear, they will be dropped no matter which model > you employ. > As a result, a simple way to get what you need (not very elegant though) is > to run a -reg- or -probit- or -logit- with all your dummies as independents > and generate a global or local with the names in the coefficient vector i.e. > : > > reg DEPENDENT dummy1 dummy2 ..... dummy500 > > global list : colnames e(b) or > > local list : colnames e(b) > > Then you can use this $list or `list' in your subsequent estimations... > > Hope this helps, > _____________ - _______________ > > Achilleas Vassilopoulos > > Agricultural University of Athens, > Dept. of Agricultural Economics and Rural Development, > Lab. of Political Economy and European Integration. > Iera Odos 75, 11855, Athens, Greece > > Tel: (+30) 210-5294726 > Fax: (+30) 2105294786 > e-mail : avassilopoulos.aua@gmail.com > > -----Original Message----- > From: owner-statalist@hsphsun2.harvard.edu > [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of richard boylan > Sent: Wednesday, September 08, 2010 10:14 PM > To: statalist@hsphsun2.harvard.edu > Subject: st: condivreg/Multicollinearity > > I am estimating a model with a very large number of interacting dummy > variables in the > first stage (> 500); so it is difficult a priori to determine which > dummy variables are going > to be collinear. > > When I estimate the model with ivreg, STATA eliminates a variety of > collinear variables > and produces estimates. However, when I use condivreg I get an error > message > > r(498); > > and a message "Multicollinearity!" > > It seems to me that one way of trying to solve this problem is to > obtain from ivreg the list > of variables that were not dropped in the first stage, and then > estimate condivreg using > the same variables. > > If this seems like a reasonable way of going about it, can anyone > point me about how > I would go about doing that? I.e., putting in a local variable the > list of variables that > were used in the first stage? > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/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/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/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/statalist/faq * http://www.ats.ucla.edu/stat/stata/