Efficiencies of Nine Two-Phase Ratio Estimators for the Mean
九种有限总体均值两阶段比率估计量的效率
Nine two-phase ratio estimators for the mean of a finite population are presented. Assuming a linear model, exact expressions for their biases and mean squared errors are derived. Then the nine estimators are compared as to bias and mean squared error. The list of estimators includes the Jackknife estimator and four modifications; two of the proposed modifications are implemented by first expressing the classical estimator in the form of a regression estimator.