TY - JOUR T1 - Some Improvment in the Estimation of Population Mean in Cluster Sampling TT - بهبود در براورد میانگین جامعه در نمونه‌گیری خوشه‌ای JF - srtc-jsri JO - srtc-jsri VL - 9 IS - 2 UR - http://jsri.srtc.ac.ir/article-1-62-en.html Y1 - 2013 SP - 159 EP - 177 KW - Auxiliary variables KW - cluster sampling KW - estimator KW - stratified sampling. N2 - Gupta and Shabbir (2008) have suggested an alternative form of ratio-type estimator for estimating the population mean. In this paper, we introduced new estimators by mixing two, stratified and cluster sampling method. Then we improved these estimators by using auxiliary variables and introducing new estimators. For sampling in infinite populations with a high geographic dispersion, the population will be divided into some smaller sub-population which leads to dispersion reduction to some extent. This will affect the variance of the estimator. Additionally dividing the population will result in saving cost, time and eases calculations. M3 10.18869/acadpub.jsri.9.2.159 ER -