Sampling with unequal probabilities and without replacement - A rejective method - ARCHIVED

Description: An alternative to the direct selection of sample is suggested, which while retaining the efficiency at the same level simplifies the selection and variance estimation processes in a wide variety of situations. If n* is the largest feasible pPS sample size that can be drawn from a given population of size N, then the proposed method entails selection of m (=N - n*) units using a pPS scheme and rejecting these units from the population such that the remainder is a pPS sample of n* units; the final sample of n units is then selected as a subsample from the remainder set. This method for selecting the pPS sample can be seen as an analogue of SRS where it is well known that the “unsampled” part of the population as well as any subsample from this part are also SRS from the entire population when SRS is the procedure used. The method is very practical for situations where m is less than the actual sample size n. Moreover, the method has the additional advantage in the context of continuing surveys, e.g. Canadian Labour Force Survey (LFS), where the number of primary sampling units (PSU’s) may have to be increased (or decreased) subsequent to the initial selection of the sample. The method also has advantages in the case of sample rotation. Main features of the proposed scheme and its limitations are given. Efficiency of the method is also evaluated empirically.

Issue Number: 1979002