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From |
"Martin Weiss" <martin.weiss1@gmx.de> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: Re: st: RE: problem with factor variable and margins. |

Date |
Wed, 17 Mar 2010 19:16:48 +0100 |

<> " I am curious if you would get this same error if you did set varabbrev, off" I cannot see much of a difference, whether -varabbrev- is on or off: ************* clear* set obs 10000 gen nainc_ainc=rnormal() gen byte nainc= /* */ irecode(_n,0,1000,3000, 5000,10000) gen x1=rnormal() gen y=2+ nainc+2*nainc_ainc+x1+ rnormal() //abbrev on qui set varabbrev on query other qui reg y x1 i.nainc nainc_ainc margins, dydx(nainc_ainc nainc) //abbrev off qui set varabbrev off query other qui reg y x1 i.nainc nainc_ainc margins, dydx(nainc_ainc nainc) ************* HTH Martin -----Original Message----- From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Christopher Baum Sent: Mittwoch, 17. März 2010 18:35 To: statalist@hsphsun2.harvard.edu Subject: re: Re: st: RE: problem with factor variable and margins. <> Rich said I think I have tracked down the problem. In addition to the factor variable nainc, I have a continuous variable nainc_ainc as a regressor (which is the indicator times a continuous variable). The margins command then got confused and assumed that nainc was an abbreviation for nainc_ainc, which did appear in the results and subsequent tests. When I rename nainc_ainc as n2ainc_ainc, my problem goes away -- a marginal effect for the discrete change in the factor variable nainc does indeed show up in the results. If I am right in diagnosing why the rename solves the problem, this means there is a bug in stata's margins. It is not reporting an ambiguous abbreviation, it is simply picking one. Should I report it to stata's tech staff, or is that something you do, Martin? Although there may indeed be a need for revision of -margins- code, I am curious if you would get this same error if you did set varabbrev, off I would recommend set varabbrev off, permanent Kit Baum | Boston College Economics and DIW Berlin | http://ideas.repec.org/e/pba1.html An Introduction to Stata Programming | http://www.stata-press.com/books/isp.html An Introduction to Modern Econometrics Using Stata | http://www.stata-press.com/books/imeus.html * * 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/

**References**:**re: Re: st: RE: problem with factor variable and margins.***From:*Christopher Baum <baum@bc.edu>

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