Abstract: The rule of three gives 3/n as the upper 95% bound for the success rate of the zero-numerator problems. However, this bound is usu ally conservative although it is useful in practice. Some Bayesian methods with beta distributions as priors have been studied. However, choosing the parameters for the priors is subjective and can severely impact the corre sponding posterior distributions. In this paper, some hierarchical models are proposed, which provide practitioners other options for those zero-numerator problems.