st: svyset for stratified probability proportional to size design

[Steve <drlead@prodigy.net.mx>]

Dear Stata list folk,

We run on Stata 9, updated all July 5.

We have a complex survey design data set with the first stage stratified
into two parts.  The primary sampling units (census tracts) have been drawn
with replacement from each of the two strata with probability proportional
to population size (PPS) in each of the strata.

We have the total population, the population of each stratum, and the
population of each PSU.  There are two further stages in the sampling
design, random sampling of 3 blocks within each PSU without replacement and
random sampling of 2 households within each block without replacement.

Our difficulty lies in specifying specifying svyset for this design,
particularly selecting (or not) the pw weights for the first level.  On the
one hand, we read from texts that the glory of probability proportional to
population sample is that it doesn't need weights.  On the other hand, we
see from svyset examples at the UCLA site, that considerable effort has 
gone
into calculating the values for the first stage weights, though without
access to the text, we are unclear how to apply their example.

Could any suggest how to at least set up svyset for the first stage of the
above described design?

Many thanks,
Steve Rothenberg
Instituto Nacional de Salud P�blica
Cuernavaca, M�xico


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