With a solid physiological severity calculator and the ISS you can study patients with unexpected outcome in a scatter plot. The diagonal on the graph is the line of 50% probability of survival/Ps. Patients under the line (lower-left)
had had injuries of low severity, Ps >50, but they died; they are the unexpected negatives. The patients to the upper-right had Ps <50 and still survived, they are the unexpected positives. From these two categories of patients we have a lot to
learn. The trauma team should do “file autopsy” on all these cases to identify failure and success factors. Decision-tree analysis may be a useful method to study this subset.