The WEIGHT statement specifies a variable to supply weighting values to use for each observation in estimating parameters.
If the weight of an observation is nonpositive, that observation is not used for the estimation. variable must be a numeric variable in the input data set.
An alternative weighting method is to use an assignment statement to give values to the special variable _WEIGHT_. The _WEIGHT_ variable must not depend on the parameters being estimated. If both weighting specifications are given, the weights are multiplied together.