A research note on the methodological and theoretical considerations for assessing crime forecasting accuracy with the predictive accuracy index

•The Predictive Accuracy Index is a common metric utilized to indicate how accurate crime forecasting techniques are when predicting future crime.•The PAI traditionally relies on area in the denominator, overlooking more appropriate units.•We argue that length or street segments should be considered in the denominator of the PAI calculation to better represent practical applications of crime forecasting.