A SIMPLE PROCEDURE FOR SAMPLING πpswor1

The author's 1963 procedure for selecting two units per stratum πpswor is generalized to any feasible fixed number of sample units. Simple closed expressions are given for the working probabilities at each draw but the formula for the joint probabilities of inclusion of pairs of units is recursive and tedious to apply. The stability of the variance estimator is believed to be close to the optimum that can be obtained using the Horvitz-Thompson estimator of total in situations where that estimator itself is optimal. Some suggestions are made for rotation of the sample.