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From |
"Chao Yawo" <Yawo1964@yahoo.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: svy: tabulate or proportions |

Date |
Tue, 29 Jul 2008 17:54:02 -0400 |

Thanks very much. I probably wasn't too clear in my original post I am examining the relationship between HIV testing behaviors (whether people plan to take the test, etc) and a number of socio-demographic and epidemiological variables. At a minimum, I wanted to understand the distribution of all my predictors before running crostabs procedures. I know svy: tab can produce both the estimated proportions (just like the %s displayed in frequency tables) and the crosstab estimates. And both of these allow one to make assumptions about the underlying population. Hence the question -- whether it is appropriate to use the svy: estimation commands once I am dealing with such a survey sample... or to revert to non-survey commands. thanks - CY ---------------------- On Tue, Jul 29, 2008 at 12:36 PM, Stas Kolenikov <skolenik@gmail.com> wrote: > On 7/25/08, Chao Yawo <Yawo1964@yahoo.com> wrote: >> I am using svy commands to analyze a DHS dataset. >> >> As a usual prerequisite, I want to run some descriptive statistics on >> my sample. I can use the regular tabulate or fre commainnd to produce >> frequency distributions. >> >> However, I realized that svy has a "tabulate" or "proportions" option >> that could produce frequency distributions/estimates per variable. I >> run both and realized slight differences between the two frequencies >> outputs. >> >> Which one should I use - I am leaning towards using the one with the >> svy: prefix. >> >> I would appreciate any thoughts and pointers. > > Well as Steven said, what is it exactly that you want to figure out? > If you want to see whether you have cells with zero or low counts, > then either -tab- or -svy : tab- will do. If you want to get any idea > of the underlying population, you MUST use -svy-. > > Let's think through a grocery shopping example. Suppose somebody > looked at your fridge and counted how many gallons of milk you have > there, how many eggs, the total weight of vegetables, etc. If they > want to figure out a diet of a given person, then that's all the data > they need. If they wanted to figure out what's available in your > grocery store, or what's a diet of an average person, then there is > more work to do: they need to figure out how often you buy any > particular food. May be you are a vegetarian, and skip the meat rows > in your supermarket -- so your fridge will not provide any information > about meat consumption, and estimates of protein intake based on your > fridge only will be biased. The "how frequently" question is what you > also know as sampling weights, based on inverse probabilities of > selection. > > So if you want something that's specific to your sample, you can have > a go without -svy- options. Will that be interesting to anybody? > Probably not. Whichever summaries you want to produce out of your data > will only be interesting to the extent that they describe the > population -- and then you need to use the survey design information. > > -- > Stas Kolenikov, also found at http://stas.kolenikov.name > Small print: I use this email account for mailing lists only. > * > * 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/

**References**:**st: svy: tabulate or proportions***From:*"Chao Yawo" <Yawo1964@yahoo.com>

**Re: st: svy: tabulate or proportions***From:*"Stas Kolenikov" <skolenik@gmail.com>

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