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 two-phase (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, 2004 and Rao, 1986 estimator have been made. The results obtained are demonstrated with the help of an empirical study.