italian journal of pure and applied mathematics-n. 28−2011 (135−142) 135 IMPROVEMENT IN ESTIMATING POPULATION MEAN USING TWO AUXILIARY VARIABLES IN TWO-PHASE SAMPLING

Rajesh Singh, Pankaj Chauhan, Nirmala Sawan, Florentin Smarandache
This study proposes improved chain-ratio type estimator for estimating population mean using some known values of population parameter(s) of the second auxiliary character. The proposed estimators have been compared with two-phase ratio estimator and some other chain type estimators. The performances of the proposed estimators have been supposed with a numerical illustration.