Unbiased ratio-type variance estimation

Based on auxiliary information, certain new ratio-type strategies for estimating the population variance, aside from the existing ones that are biased, have been proposed with a view to achieving unbiasedness for them via appropriate sampling schemes. While mooting one of the estimators, consideration has been shown to the fact that knowledge of the population mean is available. Relative performance of these estimators has also been examined.Unbiased estimators of the population variance Sampling schemes