Case-by-case matching is a technique for analyzing field accident data. The technique involves matching an accident with a group of other accidents on the basis of similar vehicle and occupant factors. The injury severity of the occupant is then compared to the injury severities of the matched occupants.

This paper will discuss some of the important issues of using case-by-case matching. The following are some of the topics which will be addressed:​

1. Criteria for the collection of accidents.
2. Choice of vehicle and occupant factors for matching.
3. Importance of matching all accidents.
4. Matching process.
5. Method of analyzing the matched data.

The paper concludes by presenting a study done on the Air Cushion Restraint System (ACRS) data using the case-by-case matching technique.