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From |
Steve Samuels <sjsamuels@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Re: st. aweight |

Date |
Mon, 29 Oct 2012 21:38:46 -0400 |

Two points: 1. In a well-designed probability sample, the sum of non-normalized probability weights is an estimate of population size. In the sampling literature, the standard symbol for population size is "N", and the symbol for sample size is "n". So, Rita's usage is correct. 2. -aweights- are _not_ restricted to integers. See http://www.stata.com/statalist/archive/2004-11/msg00274.html for an interesting thread about the relationship of analytic weights and probability weights. Steve On Oct 29, 2012, at 6:15 PM, JVerkuilen (Gmail) wrote: On Mon, Oct 29, 2012 at 5:44 PM, Rita Luk <Rita.Luk@camh.ca> wrote: > > Hi Jverkulien, > > I am slow to pick up what you say. For example my data has a sample size of only 5 obs, with the sanmpling wt variable wtpp: > > caseid wtpp > 1. 60.74 > 2. 700.38 > 3. 139.64 > 4. 9671.57 > 5. 1545.32 > > Sum of wtpp= N= 12117.65 > > According to what you said, what does the analytical weight look like? In addition to being normalized to sum to N, does the aweight need to be integer? In the case you discuss I think what would happen is that each of the wtpp numbers would be divided by 12117.65 and then multiplied by 5. The number you list as N is not N. N is 5. Usually aweights are used when you have several means and their sampling variances and want to generate an average mean weighted by sampling variance. The sampling variances have each means N built in. Hopefully if I'm wrong someone will chime in. * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/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/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Re: st. aweight***From:*Rita Luk <Rita.Luk@camh.ca>

**Re: st: Re: st. aweight***From:*"JVerkuilen (Gmail)" <jvverkuilen@gmail.com>

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