Two-phase sampling for selection with probability proportional to size in sample surveys

Abstract

Särndal & Swensson (1987) have given a general framework of estimation in two-phase sampling assuming arbitrary probability by sampling designs in both the phases where the selections are without replacement. This note discusses a specific with replacement version of the scheme where a ratio of two variables is suggested as a measure of size of the units and a mean of the ratios-type estimator is proposed. A comparison is made with the Raj (1965) scheme employing the difference method of estimation.