# Re: st: mean tests an fweight

 From Steven Samuels To statalist@hsphsun2.harvard.edu Subject Re: st: mean tests an fweight Date Sun, 5 Oct 2008 21:09:10 -0400

You should -svyset- you data to properly account for the sampling design. Information about the probability weights (pweights, not fweights) to use, the strata, if any, and "primary sampling units" will be in the survey documentation. Be warned that the options for - svyset- may not be simple. If you have successfully -svyset- your data, suppose "gender" is your group variable

The command: xi: svy: reg income i.gender

will do the survey equivalent of a t-test.

If the survey concepts in my first sentence are unfamiliar, find a good book a survey sampling (first choice: Sharon Lohr, 1999, Sampling: Design and Analysis. Duxbury Press; second: Lemeshow & Levy: Sampling of Populations, 3rd Edition, Wiley, which has Stata examples. I also recommend the Stata survey pages at UCLA: http:// www.ats.ucla.edu/stat/stata/topics/Survey.htm

-Steve

On Oct 5, 2008, at 7:49 PM, Leonor Saravia wrote:

Hello Statalisters,

I´m comparing the mean of a sample by group, this is, comparing the
mean of the income earned for males and females. I´m using the Stata -
ttest - command, but i´m a bit confused because this command doesn´t
allows using weights (fweights) and I think that this affects the
results, doesn´t it?
Do you know another way to compare the means of the sample using weights?

Thank you,

Leonor

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