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From |
Joerg Luedicke <joerg.luedicke@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: svy + aweights |

Date |
Thu, 10 Nov 2011 15:06:20 -0500 |

I do not quite understand what you are trying to do. Suppose we have two individuals, one measured only once and the other on, say, 3 occasions. Let's further assume that activity is measured in minutes (btw, how is your dependent variable measured?). We could have the following data: id day1 day2 day3 1 30 2 10 10 10 If you calculate the minutes per day now (whether or not this being a proper way of handling it), id#1 will end up with 30 and id#2 with 10 minutes. I do not understand why id#2 is supposed to weigh more than id#1? J. On Thu, Nov 10, 2011 at 2:34 PM, Jeph Herrin <stata@spandrel.net> wrote: > Thanks for the suggestion, but I specifically need to give more > weight to subjects which have more days of observation. For example, > I have > > svy : regress activity female BMI > > and would like this regression to give more weight to subjects which > have more days of observation. Using activity/days as the dependent > variable will not do this. > > Jeph > > On 11/10/2011 1:58 PM, Stas Kolenikov wrote: >> >> Rather than forming the mean activity per day, you might want to >> analyze this as a ratio: >> >> svy : ratio activity / day_reported >> >> or whatever would be an appropriate ratio. That way, you will get >> correct standard errors without messing with the analytical weights. >> >> On Thu, Nov 10, 2011 at 1:46 PM, Jeph Herrin<stata@spandrel.net> wrote: >>> >>> I am analyzing NHANES data (see manual page for -svyset-) using -svy- >>> commands. My complication is that I am using the subset of subjects for >>> which there is activity monitoring, and the number of days monitored >>> varies >>> from 1 to 8. So - to be clear - for some subjects I have 1 day of >>> monitoring, >>> and for some I have 2 days, some I have 3, etc. My dependent variable of >>> interest is daily average activity levels, but I would like this to be >>> weighted by the number of days monitored. (This is important because >>> there >>> seems to be a clear relationship between days monitored and age, race, >>> etc). >>> >>> How do I incorporate this additional level of weighting? For instance, >>> if I use >>> >>> svy : mean depvar [aw=days] >>> >>> I get an error that weights are not reported. >>> >>> thanks, >>> Jeph >>> * >>> * 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/ >>> >> >> >> > * > * 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/ > * * 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: svy + aweights***From:*Jeph Herrin <stata@spandrel.net>

**References**:**st: svy + aweights***From:*Jeph Herrin <stata@spandrel.net>

**Re: st: svy + aweights***From:*Stas Kolenikov <skolenik@gmail.com>

**Re: st: svy + aweights***From:*Jeph Herrin <stata@spandrel.net>

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