Assessment of Exponential Methods of Estimation Under Nonresponse in Two-Occasion Successive Sampling

Improved Estimators of Population Mean under Nonresponse in Successive Sampling

“…For estimating the current population mean Y, Singh et al [15,16] have given the estimators of set s υ as…”

“…Singh et al [15] also gave the estimators of set s m for estimating the current population mean Y as…”

“…Singh et al [15] suggested the following estimators of population mean Y at the current (second) occasion by combining the estimators of sets s υ and s m as…”

“…where ϕ i (0 ≤ ϕ i ≤ 1); (i � 1, 2) are unknown constants (scalars) to be determined under certain criteria. For detailed properties of the estimators T i (i � 1, 2), readers are referred to Singh et al [15].…”

“…Estimators Based on the Unmatched Portion of the Ample s u . Looking the formulation of the estimators T 1υ given by (1) due to Singh et al [15], it is clear that the estimator T 1υ is defined in the situation, in which information on the auxiliary variable z is obtained for all the sample units υ (drawn afresh from the entire population at the second occasion), and the population mean Z of the auxiliary variable z is known, but some sample units fail to supply information on the study variable y. We note that, when suggesting the estimators for the population mean Y on the current (second) occasion, Singh et al [15] used only information on the sample mean z υ of the auxiliary variable z.…”