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From |
sjsamuels@gmail.com |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: centering for subpopulation & when using sample weights ? |

Date |
Fri, 11 Dec 2009 17:17:04 -0500 |

If you are analyzing a subpopulation, you should use the -subpop- option in Stata's survey commands. The only exception that I can think of is, if your analysis is confined to a single, small, subpopulation. For choosing a centering constant, you have two possibilities: 1) a simple whole number close to the population mean or median; for example, if a mean is 102.5, I would use "100" 2) the population mean. You can estimate this by using -svy: mean-. I recommend the first choice. If you are analyzing several subpopulations, use the same centering constant for each, even if the means differ. Otherwise you will have a difficult time comparing the intercepts. If you are analyzing only one subpopulation, use a constant close to its mean. I know nothing about the Add Health data set, but you should check whether the original sampling weights were post-stratified or "raked" , so that sample estimates more closely match the population estimates. If so, and you are analyzing a single subpopulation, you should consider using only the original sampling weights, not the post-stratified weights. Luckily, help is close at hand for making this and other decisions: the excellent Survey Research Center at Maryland. -Steve On Fri, Dec 11, 2009 at 1:28 PM, Castellanos, Karen <KCASTELLANOS@ssw.umaryland.edu> wrote: > Hi everyone, > > I am a PhD student that just found this listserv online. I am using STATA to analyze data from the Add Health dataset for my dissertation. For it, I must enter sampling weights & the primary sampling units to correct for design based effects. Although I know how to center variables, I am uncertain what is the best way to specify my subpopluation when I center. Should I use the subpop option? I am also uncertain regarding whether the sampling weights need to be taken into account and how when centering my variables. Any help you can provide is greatly appreciated. > > Thanks, > > Karen > > Karen Castellanos-Brown, MSW > PhD Candidate > Adjunct Instructor > University of Maryland School of Social Work > * * 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/

**References**:**st: centering for subpopulation & when using sample weights ?***From:*"Castellanos, Karen" <KCASTELLANOS@ssw.umaryland.edu>

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