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From |
"Andrew Wade" <awade@allenconsult.com.au> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
st: Testing whether two estimated survey means are statistically different |

Date |
Thu, 20 Oct 2011 01:45:14 +1100 |

Hello, I want to test the hypothesis that the estimated mean of a specific sub-population, is not statistically different from the estimated mean of the whole population. The means are generated from a complex survey, using two separate operations of the svy: mean command. My reading of the documentation is that this type of test, when using svy: mean, should be conducted using lincom. The problem is that lincom can only be applied (it would appear) to the most recent mean estimate. However, to estimate the means of interest, I first have to estimate the svy: mean for the population, and separately use the svy:mean, over, command to estimate the mean for the specific sub-population of interest. Is there a way of 'loading' into the lincom command a previously stored mean and variance estimate, to then test against a separate estimate? And presumably, the fact that one of the means of interest is a sub-population of the other mean, is a potential problem? Or should I simply use the manual ttesti command for this test? The code for this is: ttesti 6047 293.9012 9256.260402 79889 767.4463 39570.47905 The n values here are the weighted population counts. As noted above, the 6047 is a subset of the 79889. (it is notable here that the CI's for the two means overlap, but that the test doesn't find the two estimates to be statistically difference from each other) Or should I assume unequal variances... ttesti 6047 293.9012 9256.260402 79889 767.4463 39570.47905 , unequal This 2nd ttesti approach does find the estimates to be statistically different to each other, due to a much lower s.e. estimate. Keen for any suggestions. Regards, Andrew Andrew Wade | Principal Consultant The Allen Consulting Group Level 9, 60 Collins Street, Melbourne VIC 3000 T: 03 8650 6000 | DDL: 03 8650 6043 | F: 03 9654 6363 | M: 0448 367 298 awade@allenconsult.com.au | www.allenconsult.com.au This email has been scanned for viruses and is virus free. If you encounter an email from us that has a virus please let us know immediately at virus@allenconsult.com.au. This email and any attachments are confidential and are intended solely for the use of the addressee and may contain material protected by privilege. If you are not the addressee or the person responsible for delivering the e-mail to the addressee, be advised that you have received this e-mail in error and that any use, dissemination, printing, or copying of this e-mail and any attachments is strictly prohibited. If you received it in error, please notify us immediately, delete it from your system and destroy any copies. * * 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: Testing whether two estimated survey means are statistically different***From:*Austin Nichols <austinnichols@gmail.com>

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