Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: Three and multi-stage cluster sampling commands

From   [email protected] (Jeff Pitblado, StataCorp LP)
To   [email protected]
Subject   Re: st: Three and multi-stage cluster sampling commands
Date   Wed, 06 Jul 2005 17:36:50 -0500

Moises E. Rosas <[email protected]> asks about how to specify a
multistage sampling design for analyzing survey data:

> I'm wondering what the commands are for the subject, as I have found those
> for two-stage cluster sampling so far, and a wizard for multi-stage sampling
> plans in SPSS but none in Stata. I�m a kind of novice on Stata.

The linearized variance estimator for multistage survey designs is a new
feature of Stata 9.  Use the -svyset- command to specify the survey design
variables, then use the -svy- prefix with the estimation command that fits
your model of interest.  See -help survey- for list of estimation commands
that work with the -svy- prefix.

*** Example of -svyset-ing a multistage design:

Suppose we have a dataset from the following three-stage survey where each
stage was sampled without replacement.

Stage 1:  we stratified on state and selected counties within each state.
Stage 2:  we selected schools within each sampled county.
Stage 3:  we selected 10% of the students within each sampled school.

In Stata 9, this would be specified by

	. svyset county [pw=wgt], strata(state) fpc(ncounties)
	      || school, fpc(nschools)
	      || _n, fpc(nstudents)

where 'wgt' is the variable that contains the sampling weights,

Stage 1:
	'state' identifies a state (e.g. "Texas")
	'county' identifies a county within the state (e.g. "Brazos")
	'ncounties' contains the number of counties in each state

Stage 2:
	'school' identifies the schools within each 'county'
	'nschools' contains the number of schools within each sampled county

Stage 3:
	_n indicates that the observations represent the sampled students
	'nstudents' contains the number of students within the sampled school

For more examples, see -[SVY] svyset- in the Stata 9 Survey Data Reference

[email protected]
*   For searches and help try:

© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index