Simple indicators of crime by time of day

Crime varies greatly by hour of day – more than by any other variable. Yet numbers of cases decline greatly when fragmented into hourly counts. Summary indicators are needed to conserve degrees of freedom, while making hourly information available for description and analysis. This paper describes some new indicators that summarize hour-of-day variations. A basic decision is to pick the first hour of the day, after which summary indicators are easily defined. These include the median hour of crime, crime quartile minutes, crime's daily timespan, and the 5-to-5 share of criminal activity; namely, that occurring between 5.00 AM and 4.59 PM. Each summary indicator conserves cases while offering something suitable to forecast.