Sull'efficienza della stratificazione basata sul modello

Abstract

The aim of this paper is to verify the validity of the model-based approach in sampling from finite populations. Standard sampling techniques are compared to model-based sampling with reference to stratified sampling. In particular, we compare the strategies of Dalenius and Hodges, which regard optimum and proportional allocation and the use of auxiliary variables, in contrast with the sampling strategies which use model-based stratification with a uniform allocation. These comparisons are made verifying the efficiency of the above mentioned estimators with respect to the lower bound variance of the Horvitz-Thompson estimator. We assume a linear model of superpopulation and a gamma distribution of the auxiliary variable.