BBD-COMPUTER SOFTWARE FOR FITTING THE BETA-BINOMIAL DISTRIBUTION TO DISEASE INCIDENCE DATA

A software program for DOS-based personal computers was developed to f it the beta-binomial distribution to the frequency of incidence of dis ease. The beta-binomial is a discrete distribution, which is appropria te for describing aggregated or clustered binary data such as incidenc e. Variance-ratio and C(alpha) tests are performed to determine if the re is evidence that incidence is aggregated. The program then calculat es distribution parameters and their standard errors using a maximum l ikelihood procedure, determines the expected values of the distributio n, and calculates a chi-square goodness-of-fit test. For comparison pu rposes, the program fits the binomial distribution to the same data. T he software and a detailed user's manual are available free from eithe r author.