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From |
Richard Williams <richardwilliams.ndu@gmail.com> |

To |
statalist@hsphsun2.harvard.edu, statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Factor variable notation vs. hand made dummy vars |

Date |
Mon, 06 Feb 2012 10:53:55 -0500 |

At 10:41 AM 2/6/2012, Brendan Halpin wrote:

To put the "why" back one step, the immediate reason is evident from the output | . logit for mpg d2-d5 | | note: d2 != 0 predicts failure perfectly | d2 dropped and 8 obs not used | | [...] | | . logit for mpg ib1.rep78 | | note: 1.rep78 != 0 predicts failure perfectly | 1.rep78 dropped and 2 obs not used | | note: 2.rep78 != 0 predicts failure perfectly | 2.rep78 dropped and 8 obs not used | | note: 5.rep78 omitted because of collinearity | | [...] You end up fitting different models on different data. The question is now why do the formulations behave differently, and which is the better default? Brendan

glm for mpg d2-d5, link(logit) family(binomial) glm for mpg ib1.rep78, link(logit) family(binomial)

------------------------------------------- Richard Williams, Notre Dame Dept of Sociology OFFICE: (574)631-6668, (574)631-6463 HOME: (574)289-5227 EMAIL: Richard.A.Williams.5@ND.Edu WWW: http://www.nd.edu/~rwilliam * * 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**:**st: Factor variable notation vs. hand made dummy vars***From:*Ulrich Kohler <kohler@wzb.eu>

**Re: st: Factor variable notation vs. hand made dummy vars***From:*brendan.halpin@ul.ie (Brendan Halpin)

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