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From |
jpitblado@stata.com (Jeff Pitblado, StataCorp LP) |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: What does 'ssss' mean with replication dots? |

Date |
Fri, 06 Nov 2009 17:59:40 -0600 |

Philip Burgess <philip.burgess.uq@gmail.com> is using -svy jackknife- and noticed that there were 's' characters sprinkled in with the dots displayed for each jackknife replicate: > I have two independent complex survey designs, one with 30 JK > replicate weights (survey conducted in 1997), the other with 60 > (survey conducted in 2007). > > I have combined these files in a manner similar to the Californian > Health Interview Surveys - http://www.chis.ucla.edu/methodology.html > (see the Methodology Paper on Examining Trends ... - this has detailed > instructions regarding how to combine such data with STATA). > > So, my combined file has 90 replicate weights. > > I svyset with the following command: > > - svyset [pweight=mhsfinwt], jkrweight(wpm0101 - wpm0190, > multiplier(1)) vce(jackknife) mse - > > When processing this design, for say, estimating propotions for the two surveys: > > - svy jackknife : proportion mhpsyo12, over(nsmhwb) > (running proportion on estimation sample) > > Jackknife replications (90) > ----+--- 1 ---+--- 2 ---+--- 3 ---+--- 4 ---+--- 5 > .................................................. 50 > ..........ssssssssssssssssssssssssssssss > > What does the 'ssss...' mean? 's' is one of those special codes like 'e' and 'n'; 'e' and 'n' are documented with the -dots- option in -[SVY] svy jackknife-. 's' indicates that the corresponding replicate contributes nothing to the variance estimate because the omitted PSU does not overlap with any observations in the subpopulation. For example, in the delete-1 jackknife this will occur when a PSU is in the estimation sample but is outside the subpopulation sample. When replicate weight variables are -svyset-, this can only happen if the values of the replicate weight variable are equal to the original sampling weight within the estimation sample. Given Philip's -svyset- command, it appears that -- within the estimation sample -- the last 30 replicate weight variables do not differ from the -mhsfinwt- variable. In a future update, we will modify the help file for -svy jackknife- to document the 's' character (like the 'e' and 'n' "dots"). --Jeff jpitblado@stata.com * * 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: What does 'ssss' mean with replication dots?***From:*Stas Kolenikov <skolenik@gmail.com>

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