Multiphase Sampling in Nonresponse Problems

Abstract

The sampling procedure involving subsampling of nonrespondents is discussed. A rule for selecting a subsample of nonrespondents is proposed under which the subsampling fraction is not kept constant, but varied according to the sample nonresponse rates. Using this sampling rule, the variance of the estimator of the population mean is independent of the unknown rate of nonresponse in the population. This rule provides a procedure for determining the initial sample size and subsampling fraction in order to have a desired precision of the estimator when the rate of nonresponse is not accurately known. Similar sampling rules for the selection of subsamples when several attempts are made for obtaining information are also proposed.