Improved estimation of population mean under two-phase sampling with subsampling the non-respondents

This paper considers the problem of estimating the population mean Y of the study variate y with two auxiliary variates x and z in the presence of non-response using twophase (double) sampling procedure. Four classes of combined regression and ratio estimators have been defined in four different situations and their properties are studied under large sample approximation. Comparisons of the suggested classes of estimators with usual unbiased estimator y reported by Hansen and Hurwitz (1946), Khare and Srivastava’s (1995) estimator, Okafor and Lee’s (2000) estimator and Tabasum and Khan’s (2004, 2006) estimator have been made. The results obtained are demonstrated with the help of an empirical study. & 2010 Elsevier B.V. All rights reserved.