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From |
Stephen O Neill <stepheno_neill_1999@yahoo.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: non-constant Frequency weights |

Date |
Tue, 26 Oct 2010 14:01:01 -0700 (PDT) |

Thats great - thank you very much for your help Steve - I really appreciate it. Stephen ----- Original Message ---- From: Steven Samuels <sjsamuels@gmail.com> To: statalist@hsphsun2.harvard.edu Sent: Tue, October 26, 2010 9:56:34 PM Subject: Re: st: RE: non-constant Frequency weights -- Thanks, Stephen. To answer your question: If the panels is based ona sample of the population in the first year, then use that first year weight. If the panel is a rotating panel, with individuals entering in different years, than for those individuals, use the weight for their first year. The weights in different years are useful for presenting cross-sectional statistics for each of the years, but not for the panel analysis. Also, the weights should not be specified as probability weights, not frequency weights. A frequency weight equal to K, say, is intended for use when there are K individuals in the _sample_ with identical values. If you tell a commandthat the weights are frequency weight, then you are saying that the sample size is equal to the population size. Regards, Steve Steven J. Samuels sjsamuels@gmail.com 18 Cantine's Island Saugerties NY 12477 USA Voice: 845-246-0774 Fax: 206-202-4783 On Oct 26, 2010, at 4:34 PM, Stephen O Neill wrote: Hi Steve, My data is from a survey which contains weights representing the number of inidividuals in the population represented by each sample observation. However in differnt years this frequency weight is different i.e. the number of population individuals the sample observation represents changes from year to year. Hope this clarifies, Stephen ----- Original Message ---- From: Steven Samuels <sjsamuels@gmail.com> To: statalist@hsphsun2.harvard.edu Sent: Tue, October 26, 2010 7:40:47 PM Subject: Re: st: RE: non-constant Frequency weights Stephen O Neill: Off-topic, but I'm curious: How can you have repeated identical observations on one individual at a single time point, which is what a frequency weight>1 would imply? Steve sjsamuels@gmail.com On Oct 26, 2010, at 2:28 PM, Nick Cox wrote: Fair enough. Now you have a specific question, to which I don't know the answer; but someone else may have specific advice. Nick n.j.cox@durham.ac.uk Stephen O Neill When I try to run - xtreg,fe - I get the error message "weight must be constant within ID", where ID is my unique identifier for each individual and is constant for an individual over time. I also wanteed to use the user written - xtabond2 - or some other dynamic model but it appears that weights can't be used with these. Nick Cox <n.j.cox@durham.ac.uk> I don't see the connections between these statements. A variable containing frequency weights can vary between observations, in this instance within panels as well as between panels, so that is not a problem in itself. Perhaps some particular procedures have more restricted assumptions, but you don't say what they are. Stephen O Neill I am using unbalanced panel data which contains a frequency weight each year. However the weight is not constant through time with the result that I cannot weight the data using - [fweight = weight] - . I was just wondering if there is a simple work around? * * 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/ * * 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/

**Follow-Ups**:**Re: st: RE: non-constant Frequency weights***From:*Steven Samuels <sjsamuels@gmail.com>

**References**:**st: non-constant Frequency weights***From:*Stephen O Neill <stepheno_neill_1999@yahoo.com>

**st: RE: non-constant Frequency weights***From:*Nick Cox <n.j.cox@durham.ac.uk>

**Re: st: RE: non-constant Frequency weights***From:*Stephen O Neill <stepheno_neill_1999@yahoo.com>

**RE: st: RE: non-constant Frequency weights***From:*Nick Cox <n.j.cox@durham.ac.uk>

**Re: st: RE: non-constant Frequency weights***From:*Steven Samuels <sjsamuels@gmail.com>

**Re: st: RE: non-constant Frequency weights***From:*Stephen O Neill <stepheno_neill_1999@yahoo.com>

**Re: st: RE: non-constant Frequency weights***From:*Steven Samuels <sjsamuels@gmail.com>

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