A new difference estimator has been constructed in two-phase sampling using two auxiliary variables w and x .The first phase sampling unit has been selected with probability proportional to measure of size and second phase sample is selected with equal probability without replacement. The proposed estimator has been found to be more efficient as compared to Raj (1965) in which single auxiliary ...

Designing an efficient large-area survey is a challenge, especially in environmental science when many populations are rare and clustered. Adaptive and unequal probability sampling designs are appealing when populations are rare and clustered because survey effort can be targeted to subareas of high interest. For example, higher density subareas are usually of more interest than lower density a...

In two-phase sampling, the second-phase sample is often a stratified sample based on the information observed in the first-phase sample. For the total of a population characteristic, either the double-expansion estimator or the reweighted expansion estimator can be used. Given a consistent first-phase replication variance estimator, we propose a consistent variance estimator that is applicable ...

Submitted: May 23, 2013; Accepted: Jul 3, 2013; Published: Jul 19, 2013 Abstract: This paper deals with the problem of estimating the finite population mean when some information on two auxiliary attributes are available. It is shown that the proposed estimator is more efficient than the usual mean estimator and other existing estimators. The study is also extended to two-phase sampling. The re...

Various approaches to obtaining estimates based on preliminary data are outlined. A case is then considered which frequently arises when selecting a subsample of units, the information for which is collected within a deadline that allows preliminary estimates to be produced. At the moment when these estimates have to be produced it often occurs that, although the collection of data on subsample...

The auxiliary information has always been a source of improvement in estimation of certain population characteristics. Several estimators have been developed in single and two phase sampling which utilizes information on auxiliary variables as well as auxiliary attributes. The classical estimators which use information on auxiliary variables are the ratio and regression estimators as given in H...