Dear Statalisters:
Can anyone give me some guidance on how to analyze the Survey of Income
and Program Participation ( SIPP), especially the 1996 version, to take
account of the complex sample design? I have access to both SAS/SUDAAN
and Stata.
Assuming for the moment that I use the svy commands in Stata and that I
want to do longitudinal analysis, I think I want to use the svyset
command as follows:
svyset wpfinwgt, strata(gvarstr)
where wpfinwgt is the longitudinal weight for individuals and gvarstr is
the "variance stratum code".
I am confused about whether I can or should do anything with the
options for PSU and FPC.
According to the SIPP Manual
http://www.census.gov/apsd/techdoc/sipp/sipp96l.pdf page 8-1:
"The 1996 Panel of the SIPP sample is located in 322 Primary Sampling
Units (PSUs), each
consisting of a county or a group of contiguous counties. Within these
PSUs, living quarters
(LQs) were systematically selected from lists of addresses...."
As far as I can tell, there is no SIPP variable for the PSU. The PSU
code is scrambled inside the ssuid variable (the household ID number)
but I do not think there is any way to tell which ssuids came from the
same PSU.
However, from reading the Stata 8 manual at U [30] p. 346-347 I wonder
if I should use the command:
svyset wpfinwgt, strata(gvarstr) psu(ssuid) fpc(epppnum)
where epppnum is the individual person identifier within the household.
I think this is wrong but my logic here is that the SIPP is sampling
individuals who are "clustered" in households where every member of the
household is interviewed. I am particularly concerned about the remark
in the Stata Manual U 30.2.2 p. 347 "For example if our PSUs were were
households and we included every member of the household in our study,
then a finite population correction term would be appropriate where the
households are sampled using simple random sampling without replacement
in each stratum"
Guidance would be much appreciated.
--
Stephen T. Mennemeyer Ph.D.
University of Alabama at Birmingham
School of Public Health
Dept. of Health Care Organization and Policy
U.S. Mail:
1530 3rd Ave. South 330 RPHB
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1665 University Blvd.
Birmingham, Al 35294-0022
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e-mail: [email protected]
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