Some improved ratio-type estimators of finite population variance in sample surveys

Abstract

This paper proposes a class of ratio-type estimators of finite population variance and variance ratio when the population variance of an auxiliary character is known. Asymptotic expressions for bias and mean square error are derived and their MSE's are compared with the MSE of usual ratio estimator t₁ proposed by Isaki (1983) of the population variance of study character y. The regions are obtained under which proposed estimator is superior to t₁ . When a prior knowledge of the value of coefficient of kurtosis, ;β₂(y)of y is a t hand, ratio type estimator, say t₂, of is suggested. It is shown, under certain conditions, that t₂ is more efficient than t₁. Under some further knowledge another estimator of , better than t₁ and t₂,is proposed. Finally, one more class of estimator is proposed and its properties are discussed. The discussions are also made in bivariate normal population

Keywords:

• Population variance
• population variance ratio
• prior information
• mean square error