Evaluation of paternity‐testing data from the joint distribution of paternity index and rate of exclusion

We examine the behavior of the joint distribution of exclusion rate (P_E) and paternity index (L) when combining the information from an increasing number of genetic marker systems. The (1n(1‐P_E), 1n L) distribution for fathers as well as for non‐excluded non‐fathers approaches Bivariate Normality very rapidly as the number of systems increases. The fit is almost perfect when based on only seven systems frequently employed in paternity diagnosis. We argue that a procedure for evaluation of paternity testing data that is based on the distribution of (1n(1‐P_E), 1n L)‐values among fathers and non‐fathers would yield a considerably greater power than currently practiced techniques.