title: Study design and sample size considerations for half-life studies.
abstract: Most studies on the half-lives of environmental contaminants have been based on small sample sizes and a limited number of repeated measurements. In this paper, we address issues of study design and sample size for half-life studies. Useful guidelines are provided for choosing the number of repeats and the optimal time interval between repeats for estimating an individual's half-life with a given level of precision, while minimizing the cost of the study. In addition, sample size and power considerations for studies comparing two population half-lives are investigated. An example is presented using data from a study on polychlorinated biphenyls and breast cancer.
authors.affiliation: Institute of Environmental Medicine and Kaplan Comprehensive Cancer Center, New York University Medical Center, NY 10010, USA.
authors.forename: M Y
authors.initials: MY
authors.lastname: Kim
authors.forename: N
authors.initials: N
authors.lastname: Dubin
mesh_terms: D001943:Breast Neoplasms / Q000139:chemically induced; D004785:Environmental Pollutants / Q000493:pharmacokinetics*; D006207:Half-Life; D011078:Polychlorinated Biphenyls / Q000633:toxicity; D012107:Research Design; D018401:Sample Size
chemical_list: D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls