📖 Use of auxiliary information has been extensively used in survey sampling to increase the precision of the estimates. Ratio and Regression methods are most popular methods that utilizes information of auxiliary attributes. The auxiliary information has also been used in two-phase sampling for estimation of population characteristics. In this book use of auxiliary attributes have been proposed in two-phase sampling. Several methods have been proposed by using information on auxiliary attributes. The generalized ratio and regression families have been suggested. We have also proposed the shrinkage estimators by using information of multiple auxiliary attributes.