ABSTRACT
Ratio and regression estimation use variables that are correlated with the variable of interest to improve the precision of estimators of the mean and total of a population. The concept of ratio estimation is completely general and is easily extended to other sampling designs. D. L. Steffey et al. describe the use of combined ratio estimation in the legal case Labor Ready v. Gates McDonald. Under the ratio model, the point estimator for the population total is the same as in the design-based approach, but the variance differs from that for the design-based estimator. Ratio and regression estimation use an auxiliary variable that is highly correlated with the variable of interest to reduce the mean squared error mean squared error of estimated population means or totals. An estimator of the population mean or total based on a ratio with an auxiliary quantity for which the populations mean or total is known.
