Estimation of the Fifth Percentile Using a Subset of Order Statistics

Estimation of the fifth percentile using a subset of order statistics is closely related to the water quality standards in the United States. We focus on the subsample size to estimate it. Because the possibility and consequences of skewness of the original data give a good reason to restrict the subsample size, the subsample size of 2 is recommended in this paper. We also evaluate the estimator of a Final Acute Value (FAV) analytically, based on the subsample size of 2 closest to 0.05.