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

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

Subject |
st: AW: -areg- question |

Date |
Thu, 17 Sep 2009 22:57:43 +0200 |

<> Are you implying that -areg- and -regress- results must differ? -areg-, as I understand it, is meant to replicate -regress- output when there are too many fixed effects for -regress- to handle. Example 1 in [R], p. 80, shows how the two commands return the same output: ************* sysuse auto, clear regress mpg weight gear_ratio b5.rep78 areg mpg weight gear_ratio, absorb(rep78) ************* HTH Martin -----Ursprüngliche Nachricht----- Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Sue Gesendet: Donnerstag, 17. September 2009 19:28 An: statalist@hsphsun2.harvard.edu Betreff: st: -areg- question Dear Statalisters, I have a question on the number of observations used in -areg-. I run the following regressions: reg `var'_mort ``var'_controls' _Irel* _Ibirth* _Icountry* _Iethn* if touse`var' [pw = weight], cluster(clus_rc) robust areg `var'_mort ``var'_controls' _Irel* _Ibirth* _Icountry* _Iethn* if touse`var' [pw = weight], absorb(mother_rc) cluster(clus_rc) robust The only difference between the two is that the second is a regression with additional fixed effects using the variable "mother_rc". I'm wondering why the number of observations is the same in both regressions, even though there are values of mother_rc(the group id) that have only one observation and should therefore be dropped and not used in the regression. I'm wondering if Stata drops those observations but still reports the total sample size, or if there's anything wrong. I'd really appreciate your input. * * 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**:**st: -areg- question***From:*Sue <likecats@gmail.com>

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