Which methodology calculates expected collision frequencies combining observed and estimated data?

The Empirical Bayes method is the correct choice for the methodology that calculates expected collision frequencies by combining observed and estimated data. This approach is widely recognized in road safety analysis because it effectively uses historical collision data from a particular site to adjust for the underlying risks associated with that site, including traffic volume and other relevant factors.

The key feature of the Empirical Bayes method is that it leverages both the empirical data collected from the site in question (observed data) and estimates of what the collision frequency would be under normal conditions without interventions (estimated data). By applying a statistical framework, this methodology helps to produce a more precise estimate of expected collisions, factoring in the reliability of past data while addressing the influence of random variations.

In contrast, the other methodologies mentioned focus on different aspects of collision analysis. The Minimum acceptable collision rate method generally sets a baseline expectation for collisions based upon a minimum standard, while the Critical collision rate method identifies specific collision rates that need to be addressed as they exceed safety thresholds. The Safe Systems method, on the other hand, promotes a holistic approach to road safety, emphasizing the design of systems to protect all road users regardless of human error. Each of these methods serves important functions in road safety, but they do not combine