A model for proportions with medical applications
Data that are proportions arise most frequently in biomedical research. In this paper, the exact distributions of $R = X + Y$ and $W = X/(X + Y)$ and the corresponding moment properties are derived when $X$ and $Y$ are proportions and arise from the most flexible bivariate beta distribution known to date. The associated estimation procedures are developed. Finally, two medical data sets are used to illustrate possible applications.