Introduction has been given in Chapter 1. In Chapter 2, history of
two-phase sampling and some well-known estimators along with their mean
square errors and biases are given. Some regression cum ratio product
estimators proposed by Hanif et al. (2009, 2010) and Hamad and Hanif
(2011) in single and two-phase sampling using two auxiliary variables
are discussed in chapter 3 and 4. The empirical study of those
estimators is undertaken in Chapter 5.