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

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Aggregated Weighted Summary Statistics Using Probability Weights |

Date |
Tue, 13 Jul 2010 22:59:37 -0400 |

Please remove the "and" from the example before running! On Tue, Jul 13, 2010 at 10:58 PM, Steve Samuels <sjsamuels@gmail.com> wrote:, > > Lindsay Newman-- > > You do not show us actual commands or results as requested by the FAQ, > > "Say exactly what you typed and exactly what Stata typed (or did) in > response. N.B. exactly! If you can, reproduce the error with one of > Stata's provided datasets or a simple concocted dataset that you > include in your posting." > > In the following example, the discrepancy between #1 and #2,#3, and > #4 is absent. > Steve > > ***************************************** > sysuse auto, clear > bys foreign: sum mpg [aw =rep78] //1 > sum mpg if foreign==0 [aw=rep78] //2 > > sysuse auto, clear > svyset _n [pweight=rep78] > svy: mean mpg if foreign==0 //3 > estat sd > > di sqrt(e(N) * el(e(V_srs),1,1)) //4 > ***************************************** > > > > On Tue, Jul 13, 2010 at 11:17 AM, Lindsay Newman <lrshorr@gmail.com> wrote: >> I am using survey data with probability weights. I want to compute >> various summary statistics, including the mean and standard deviation, >> of the data at an aggregated level. In particular, I want to use >> individual responses to certain questions to calculate the country >> year weighted mean and standard deviation of the response. For >> instance, if 200 individuals responded to a particular question, what >> is the weighted average response for that country year? What is the >> weighted standard deviation of the responses for that country year? >> >> When I sort by country year and use the following code: >> >> (1) by countryyear: summarize (response variable) [aw=weight variable] >> >> I get different results for the standard deviations than when I either run: >> >> (2) summarize (response variable) if countryyear ==x [aw=weight variable] >> >> or when I calculate the standard deviation manually using: >> >> (3) di sqrt(e(N) * el(e(V_srs),1,1)) >> >> >> When I analyze the responses for just one country year (i.e. deleting >> all but responses from a single country year) using: >> >> (4) svy: mean (response variable) estat sd, >> >> the standard deviations match 2 and 3 but not 1. Why is this? >> >> Thank you. >> * >> * 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/ >> > > > > -- > Steven Samuels > sjsamuels@gmail.com > 18 Cantine's Island > Saugerties NY 12477 > USA > Voice: 845-246-0774 > Fax: 206-202-4783 > -- Steven Samuels sjsamuels@gmail.com 18 Cantine's Island Saugerties NY 12477 USA Voice: 845-246-0774 Fax: 206-202-4783 * * 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: Aggregated Weighted Summary Statistics Using Probability Weights***From:*Lindsay Newman <lrshorr@gmail.com>

**Re: st: Aggregated Weighted Summary Statistics Using Probability Weights***From:*Steve Samuels <sjsamuels@gmail.com>

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