Paired ranked set sampling: A more efficient procedure

The usual ranked set sampling (RSS) scheme is modified and a paired ranked set sampling (PRSS) method is suggested. Estimators for population mean and standard deviation using the PRSS method are obtained. The estimator of population mean based on the PRSS is compared with simple random sampling (SRS) mean, the RSS estimator of population mean and also with the minimum variance linear unbiased estimator (MVLUE) of population mean based on RSS. The estimator of standard deviation based on the PRSS is also compared with the MVLUE of population standard deviation. The estimators of population mean and standard deviation based on PRSS are found to be more efficient than their respective counterparts for six probability distributions considered. The estimators of population mean and standard deviation based on PRSS are compared with those based on the SRS and the RSS for normal distribution where errors in ranking are present. The estimators using the PRSS method are found to be more efficient than their respective counterparts for normal distribution, even in presence of errors in ranking.