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From |
Philip Burgess <philip.burgess.uq@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Query re proportions post-standardization |

Date |
Sun, 15 Nov 2009 09:14:10 +1000 |

I have a dataset with 2 cross-sectional independent samples - the first survey conducted in 1997 & the second survey conducted in 2007. The var indicating survey year is nsmhwb - coded (0/1). My svyset statement, based on the 90 jackknife replicate weights etc, is as follows: -svyset [pweight=mhsfinwt], jkrweight(wpm0101 - wpm0190, multiplier(1)) vce(jackknife) mse- I want to compare proportions on a DV (mhpsyo12 = 0/1) by IV survey year (nsmhwb = 0/1). -svy jackknife, nodots : proportion mhpsyo12, over(nsmhwb)- The 1997 estimate is 17.0% (SE = 1.3%)' the 2007 estimate is 37.3% (SE = 2.5%). I have separately created a variable that indicate the proportion of 2007 in each of 5 age group strata (i.e., 20-29 years, 30-39 years, etc to 60-69 years). The strata var is 'st_age)'; the 2007 strata population proportion var is 'st_wt' - ranging from 0.0 to 1.0. The population structure has changed over the 10-year period (i.e., aged). So, I want to compare proportions adjusted by the 2007 strata population size I run: svy jackknife, nodots : proportion mhpsyo12, stdize(st_age) stdweight(st_wt) over(nsmhwb) The 1997 estimate is 15.5% (SE = 1.4%)' the 2007 estimate is 34.1% (SE = 2.3%). I'm puzzled that the 2007 proportion estimates change from the previous statement. I would have thought that the 2007 estimates (and their SEs) would NOT vary given the fact that standardization is based on actual 2007 proportions? I guess I'm doing something wrong - any ideas? I'm using Stata 11.0 - born 21 October 2009. Thanks; Philip * * 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: Query re proportions post-standardization***From:*Philip Burgess <philip.burgess.uq@gmail.com>

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