The best estimators

Ratio-estimator and regression estimator are examples of improving estimator. A number of ratio-type estimators are introduced to increase the efficiency of ratio estimator. In this research work a general class of ratio-type estimators which includes previous ratio-type estimators is introduced and then an approximated MSE of the general ratio-type estimator is obtained using the Taylor expansion. And with obtain the optimum values of desired parameters and substituting in the obtained MSE, the minimum MSE of this estimator is obtained that is equal to the MSE of the difference estimator. A notable discovery is that the approximated optimum estimator in the class is asymptoticallyequal to the regression estimator in the case of small similar size.

Keywords:

Auxiliary variable , ratio-type estimator , Taylor expansion , MSE