The REPWEIGHTS statement names variables that provide replicate weights for bootstrap, BRR, or jackknife variance estimation, which you request with the VARMETHOD=BOOTSTRAP, VARMETHOD=BRR, or VARMETHOD=JACKKNIFE option, respectively, in the PROC SURVEYMEANS statement. For more information about the replication methods, see the section Replication Methods for Variance Estimation.
Each REPWEIGHTS variable contains the weights for a single replicate, and the number of replicates equals the number of REPWEIGHTS variables. The REPWEIGHTS variables must be numeric, and the variable values must be nonnegative unless you specify the NEGATIVE option.
For more information about replicate weights that the SURVEYMEANS procedure creates, see the sections Balanced Repeated Replication (BRR) Method and Jackknife Method.
If you provide replicate weights with a REPWEIGHTS statement, you do not need to specify a CLUSTER or STRATA statement. If you use a REPWEIGHTS statement and do not specify the VARMETHOD= option in the PROC SURVEYMEANS statement, the procedure uses VARMETHOD=JACKKNIFE by default.
If you specify a REPWEIGHTS statement but do not include a WEIGHT statement, the procedure uses the average of replicate weights of each observation as the observation’s weight.
You can specify the following options in the REPWEIGHTS statement after a slash (/):
-
DF=df
-
specifies the degrees of freedom for the analysis. The value of df must be a positive number. By default, the value of df is the number of REPWEIGHTS variables.
If you know the number of PSUs and the number of strata from which the replicate weights are generated, you should specify the number of PSUs minus the number of strata as the degrees of freedom in this option. For more information, see the section Degrees of Freedom.
-
JKCOEFS=value | <(>values <)> | SAS-data-set
-
specifies jackknife coefficients for the VARMETHOD=JACKKNIFE option in the PROC SURVEYMEANS statement. The jackknife coefficient values must be nonnegative numbers. For more information about jackknife coefficients, see the section Jackknife Method.
You can provide jackknife coefficients by specifying one of the following forms:
-
value
specifies a single jackknife coefficient value to use for all replicates, where value must be a nonnegative number.
-
values
-
specifies a list of jackknife coefficients, where each value in the values is a nonnegative number that corresponds to a single replicate that is identified by a REPWEIGHTS variable. You can separate the values with blanks or commas, and you can optionally enclose the values in parentheses. The number of values in the values must equal the number of replicate weight variables that you specify in the REPWEIGHTS statement.
You must list the jackknife coefficient values in the same order in which you list the corresponding replicate weight variables in the REPWEIGHTS statement.
-
SAS-data-set
names a SAS-data-set that contains the jackknife coefficients, where each coefficient value must be a nonnegative number. You must provide the jackknife coefficients in the data set variable named JKCoefficient. Each observation in this data set must correspond to a replicate that is identified by a REPWEIGHTS variable. The number of observations in the SAS-data-set must not be less than the number of REPWEIGHTS variables.
-
NEGATIVE | NEG
-
removes the restriction that the REPWEIGHTS variable values must be nonnegative. When you specify this option, PROC SURVEYMEANS accepts negative replicate weight values and includes them in the analysis.
By default, replicate weight values must be nonnegative; when PROC SURVEYMEANS encounters a negative replicate weight value, it displays an error message and does not perform the analysis unless you specify the NEGATIVE option.
-
REPCOEFS=value | <(>values <)> | SAS-data-set
-
specifies replicate coefficients for the VARMETHOD=BOOTSTRAP or VARMETHOD=JACKKNIFE option in the PROC SURVEYMEANS statement, where each coefficient corresponds to an individual replicate weight that is identified by a REPWEIGHTS variable. The replicate coefficient values must be nonnegative numbers.
You can provide replicate coefficients by specifying one of the following forms:
-
value
specifies a single replicate coefficient value to use for all replicates, where value must be a nonnegative number.
-
values
-
specifies a list of replicate coefficients, where each value in the values is a nonnegative number that corresponds to a single replicate that is identified by a REPWEIGHTS variable. You can separate the values with blanks or commas, and you can optionally enclose the values in parentheses. The number of values in the values must equal the number of replicate weight variables that you specify in the REPWEIGHTS statement.
You must list the replicate coefficient values in the same order in which you list the corresponding replicate weight variables in the REPWEIGHTS statement.
-
SAS-data-set
names a SAS-data-set that contains the replicate coefficients, where each coefficient value must be a nonnegative number. You must provide the replicate coefficients in the data set variable named JKCoefficient. Each observation in this data set must correspond to a replicate that is identified by a REPWEIGHTS variable. The number of observations in the SAS-data-set must not be less than the number of REPWEIGHTS variables.