文摘
The paper considers a problem of estimating a finite population parameter T (α, β, γ) in two-phase and successive sampling. Asymptotic optimum estimator (AOE) in a class is identified with its approximate variance formula. Several estimators of different parameters are identified as particular members of the class. In particular, we have focused on estimating the population coefficient of variation. The expressions for bias and variance are derived and compared theoretically.