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Thx, Justina -----owner-statalist@hsphsun2.harvard.edu schrieb: ----- An: statalist@hsphsun2.harvard.edu Von: Maarten buis <maartenbuis@yahoo.co.uk> Gesendet von: owner-statalist@hsphsun2.harvard.edu Datum: 09.02.2011 05:56PM Thema: Re: Antwort: Re: st: Multicollinearity in panel data --- On Wed, 9/2/11, Justina Fischer wrote: > would an alternative way of dealing with a high correlation between > x and x*x and the loss in precision be to conduct tests of joint > significance (for both coefficients) ? If you can estimate the model then this might work. However, sometimes the correlation becomes so strong that Stata will drop one of the variables. Recently there was such a case on Statalist where x was year of birth and the poster wanted to add x, x^2 and x^3 and ended up with this problem. Than, obviously, no amount of joint testing can save= you (but centering your year of birth variable prior to creating the squares and cubes can). -- Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * =A0 For searches and help try: * =A0 http://www.stata.com/help.cgi?search * =A0 http://www.stata.com/support/statalist/faq * =A0 http://www.ats.ucla.edu/stat/stata/ = --0__=4EBBF2A1DFCCB5C88f9e8a93df938690918c4EBBF2A1DFCCB5C8 Content-type: text/html; charset=ISO-8859-15 Content-Disposition: inline Content-transfer-encoding: quoted-printable <html><body> <p><tt>yes, sure, if one variable gets dropped no test of joint signifi= cance can save you.<br> </tt><br> <tt>From my own experience, it works for age, age squared and age cubed= (all not demeaned), if some people are sufficiently 'aged' in the data= <br> </tt><br> <tt>Thx,<br> </tt><tt>Justina<br> </tt><tt>-----owner-statalist@hsphsun2.harvard.edu schrieb: -----<br> </tt><br> <tt>An: statalist@hsphsun2.harvard.edu<br> </tt><tt>Von: Maarten buis <maartenbuis@yahoo.co.uk><br> </tt><tt>Gesendet von: owner-statalist@hsphsun2.harvard.edu<br> </tt><tt>Datum: 09.02.2011 05:56PM<br> </tt><tt>Thema: Re: Antwort: Re: st: Multicollinearity in panel data<br= > </tt><br> <tt>--- On Wed, 9/2/11, Justina Fischer wrote:<br> </tt><tt>> would an alternative way of dealing with a high correlati= on between<br> </tt><tt>> x and x*x and the loss in precision be to conduct tests o= f joint<br> </tt><tt>> significance (for both coefficients) ?<br> </tt><br> <tt>If you can estimate the model then this might work. However, someti= mes<br> </tt><tt>the correlation becomes so strong that Stata will drop one of = the<br> </tt><tt>variables. Recently there was such a case on Statalist where x= was<br> </tt><tt>year of birth and the poster wanted to add x, x^2 and x^3 and = ended up<br> </tt><tt>with this problem. Than, obviously, no amount of joint testing= can save<br> </tt><tt>you (but centering your year of birth variable prior to creati= ng the<br> </tt><tt>squares and cubes can).<br> </tt><br> <tt>-- Maarten<br> </tt><br> <tt>--------------------------<br> </tt><tt>Maarten L. Buis<br> </tt><tt>Institut fuer Soziologie<br> </tt><tt>Universitaet Tuebingen<br> </tt><tt>Wilhelmstrasse 36<br> </tt><tt>72074 Tuebingen<br> </tt><tt>Germany<br> </tt><br> <tt><a href=3D"http://www.maartenbuis.nl";>http://www.maartenbuis.nl</a>= <br> </tt><tt>--------------------------<br> </tt><br> <br> <br> <br> <tt>*<br> </tt><tt>* =A0 For searches and help try:<br> </tt><tt>* =A0 <a href=3D"http://www.stata.com/help.cgi?search";>http://= www.stata.com/help.cgi?search</a><br> </tt><tt>* =A0 <a href=3D"http://www.stata.com/support/statalist/faq";>h= ttp://www.stata.com/support/statalist/faq</a><br> </tt><tt>* =A0 <a href=3D"http://www.ats.ucla.edu/stat/stata/";>http://w= ww.ats.ucla.edu/stat/stata/</a><br> </tt><br> </body></html>= --0__=4EBBF2A1DFCCB5C88f9e8a93df938690918c4EBBF2A1DFCCB5C8-- * * 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/