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Pooled primary sampling unit (PSU) for variance estimation


[ PRELIMINARY VARIABLE: Variable description may change once we confirm the universe and assess the comparability of this variable over time. ]

PSUPLD is the pooled variance primary sampling unit variable that represents the impact of the sample design clustering on the estimates of variance and standard errors. It is appropriate to use PSUPLD instead of the annual primary sampling unit (PSUANN) if the years included in a pooled analysis include survey year 2001 or earlier. When pooling data from only 2002 and later, use the variable PSUANN, the annual stratum variable for each survey year.

For analysis, researchers need to use PSUPLD in conjunction with STRATAPLD to account for stratification and clustering when computing variance estimates with IPUMS MEPS data.


PSUPLD should be used when analysts wish to pool together (aka combine) more than one year of MEPS annual data including any years before 2002. In most years, MEPS samples are not completely independent from one another, both because each panel is in the MEPS for two consecutive years and because households are sampled from the same geographic areas in multiple years. However, because MEPS is designed to be nationally representative in every year, multiple sample years can still be pooled. The use of PSUPLD and STRAPLD is necessary to obtain appropriate standard errors by specifying a common variance structure.


PSUPLD is a 1-digit numeric variable.

0: Not in Universe


The comparability of this variable over time has not yet been assessed.


The universe for this variable has not yet been confirmed.


  • 1996-2015


  • No weights are available for this variable. Please refer to PSUPLD for more information.


This variable has no flags.