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From |
nicola.baldini2@unibo.it |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: xtpoisson, fe: 42 groups (93 obs) dropped because of all zero outcomes! Why? |

Date |
Mon, 05 May 2008 18:24:11 +0200 |

A group in this case is all the observations which share the same value of the group/panel variable "i", as setted by the -tsset- command. If all the observation with the same value of such variable have a zero outcome, then the group is deleted. I am worried about the ratio between obs and groups: about 2 is quite a small number Nicola At 02.33 01/05/2008 -0400, "ippab ippab" wrote: >Hi Everyone, > >I am running a fixed effects model with "xtpoisson, fe" command. I am >trying to understand why the software is dropping a few observations >because of the following reason: "42 groups (93 obs) dropped because >of all zero outcomes". More specifically, I am confused with the >term all zero outcomes. How is it determining this 42 groups? My y >variable is a count and includes zeros for more than 42 groups. >Clearly, it is dropping a subset of the groups with zero y variable. >May be the answer is quite trivial; unfortunately, I am not getting >it. I would really appreciate any help. > >Thanks a lot. > >ippab * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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