Accident Metric (AM)#

Description#

AM evaluates whether an accident happened in a scenario:

\[\begin{split}\mathit{AM}(\mathit{Sc}) = \begin{cases} 0, \quad \text{no accident happened during } \mathit{Sc}, \\ 1, \quad \text{otherwise.} \end{cases}\end{split}\]

This simplistic metric is implicitly used in accident databases, such as GIDAS. It fails to identify critical non-accident scenarios.

Properties#

Run-time capability#

Target values#

Not necessary

Subject type#

Any

Scenario type#

Any

Inputs#

Any parameter combination that allows determination of whether an accident happened or not

Output scale#

\(\{0,1\}\), nominal scale

Reliability#

Low, as a change in accident outcome can be related to only minor changes in criticality (i.e. near misses)

Validity#

Medium, due to maximal specificity but low sensitivity

Sensitivity#

Low, as all critical non-accidents are missed

Specificity#

Maximal as all accidents are critical

Prediction model#

None, since a-posteriori