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From |
Rich Steinberg <rsteinbe@iupui.edu> |

To |
statalist@hsphsun2.harvard.edu |

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

Date |
Wed, 17 Mar 2010 14:19:01 -0400 |

Philip Ender wrote:

Rich wrote: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?I don't think the problem is with -margins- but with the fact that you created the interaction outside of your model. If you create the interaction using the factor variables in the model then -margins- not only identifies all of the terms but produces marginal effects that take into account the interactions. Without reproducing you entire model, it would look something like this: . tobit dv i.naic c.ainc i.naic#c.ainc ... Phil

-- Rich Steinberg Department of Economics, 516 Cavanaugh Hall IUPUI Indianapolis, IN 46202-5140 317-278-7221 "Unanswered email since 1955" * * 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/

**Follow-Ups**:**RE: st: RE: problem with factor variable and margins.***From:*"Martin Weiss" <martin.weiss1@gmx.de>

**References**:**Re: Re: st: RE: problem with factor variable and margins.***From:*Philip Ender <ender97@gmail.com>

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