title: Sample size calculations for the log rank test: a Gompertz model approach.
abstract: Sample size calculations for clinical trials dealing with survivorship are often based on an exponential model. This model is inappropriate when a non-zero proportion of the population is expected to have indefinite survival. In such cases the Gompertz model offers a reasonable alternative. A method for calculating the required accrual time for a clinical trial in which the treatment arms have Gompertz survival distributions satisfying the proportion hazards assumption is developed. A computer program to perform this method is given, as well as an iterative method that can be used when a computer is not available.
authors: Department of Pediatrics, University of Florida, Gainesville 32605.
authors: A B
authors: AB
authors: Cantor
mesh_terms: D002986:Clinical Trials as Topic; D006801:Humans; D015233:Models, Statistical; D016019:Survival Analysis