title: A note on sample size calculation for mean comparisons based on noncentral t-statistics.
abstract: One-sample and two-sample t-tests are commonly used in analyzing data from clinical trials in comparing mean responses from two drug products. During the planning stage of a clinical study, a crucial step is the sample size calculation, i.e., the determination of the number of subjects (patients) needed to achieve a desired power (e.g., 80%) for detecting a clinically meaningful difference in the mean drug responses. Based on noncentral t-distributions, we derive some sample size calculation formulas for testing equality, testing therapeutic noninferiority/superiority, and testing therapeutic equivalence, under the popular one-sample design, two-sample parallel design, and two-sample crossover design. Useful tables are constructed and some examples are given for illustration.
authors.affiliation: StatPlus, Inc., Heston Hall, Suite 206, 1790 Yardley-Langhorne Road, Yardley, PA 19067, USA.
authors.forename: Shein-Chung
authors.initials: SC
authors.lastname: Chow
authors.forename: Jun
authors.initials: J
authors.lastname: Shao
authors.forename: Hansheng
authors.initials: H
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D000924:Anticholesteremic Agents / Q000627:therapeutic use; D001851:Bone Diseases, Metabolic / Q000188:drug therapy; D008078:Cholesterol, LDL / Q000097:blood; D003327:Coronary Disease / Q000517:prevention & control; D018592:Cross-Over Studies; D003627:Data Interpretation, Statistical; D004358:Drug Therapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy; D012107:Research Design; D018401:Sample Size; D013810:Therapeutic Equivalency
chemical_list: D000924:Anticholesteremic Agents; D008078:Cholesterol, LDL