Violent crime in the United States has traveled a striking path in the past 20 years, from a sharp spike in the late 1980s to a dramatic drop beginning around 1993 that lasted until a flattening occurred at the beginning of the new century. The upturn of the 1980s was driven almost exclusively...

A hierarchical model is developed to account for selection biases that result from processes in which events have a fixed probability of being sampled, but individuals in the population generate events at varying rates. It is shown that inferences about the population parameters from such...