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The SURVEYREG Procedure |

If your analysis should include a finite population
correction (*fpc*), you can input either the
sampling rate or the population total using the RATE=
option or the TOTAL= option. You cannot specify
both of these options in the same PROC SURVEYREG
statement. If you do not specify one of these options,
the procedure does not use the *fpc* when computing
variance estimates. For fairly small sampling
fractions, it is appropriate to ignore this correction.
Refer to Cochran (1977) and Kish (1965).

If your design has multiple stages of selection and you are specifying the RATE= option, you should input the first-stage sampling rate, which is the ratio of the number of PSUs in the sample to the total number of PSUs in the study population. If you are specifying the TOTAL= option for a multistage design, you should input the total number of PSUs in the study population.

For a nonstratified sample design, or for a stratified
sample design with the same sampling rate or the same
population total in all strata, you should use the
RATE=*value* option or the TOTAL=*value* option.
If your sample design is stratified with different
sampling rates or population totals in the strata, then
you can use the RATE=*SAS-data-set* option or
the TOTAL=*SAS-data-set* option to name a SAS data
set that contains the stratum sampling rates or totals.
This data set is called a *secondary data set*, as
opposed to the *primary data set* that you specify
with the DATA= option.

The secondary data set must contain all the
stratification variables listed in the STRATA statement
and all the variables in the BY statement. If there are
formats associated with the STRATA variables and the BY
variables, then the formats must be consistent in the
primary and the secondary data sets. If you specify the
TOTAL=*SAS-data-set* option, the secondary
data set must have a variable named _TOTAL_ that
contains the stratum population totals. Or if you
specify the RATE=*SAS-data-set* option, the
secondary data set must have a variable named
_RATE_ that contains the stratum sampling rates. The
secondary data set must contain all BY and STRATA groups
that occur in the primary data set. If the secondary
data set contains more than one observation for any one
stratum, then the procedure uses the first value of
_TOTAL_ or _RATE_ for that stratum and
ignores the rest.

The *value* in the RATE= option, or the values
of _RATE_ in the secondary data set, must be
positive numbers. You can specify a sampling rate as a
number between 0 and 1. Or you can specify a sampling
rate in percentage form as a number between 1 and 100,
and PROC SURVEYREG will convert that number to a
proportion. The procedure treats the value 1 as 100%,
and not the percentage form 1%.

If you specify the TOTAL=*value* option, *value*
must not be less than the sample size. If you provide
stratum population totals in a secondary data set, these
values must not be less than the corresponding stratum
sample sizes.

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