Affiliations: World Trade Center Health Registry, Division of Epidemiology, New York City Department of Health and Mental Hygiene, 125 Worth Street, 10th Floor, New York, NY, USA | E-mail: osukhmin@health.nyc.gov
Abstract: Sub-studies addressing specific research questions may necessitate selecting a random sample from different eligibility groups of The World Trade Center Health Registry (WTCHR) for estimating population parameter mean. In such a situation, Singh (1988) and Osahan (1997) proposed three two-stage sampling strategies in overlapping clusters. These sampling strategies are compared using WTCHR’s overlapping eligibility groups, in terms of their bias and efficiency.