Ejection decisions by strike pilots: an extreme value interpretation.

BACKGROUND An explanation is offered for the asymmetry of Receiver Operating Characteristic (ROC) curves obtained from pilots' decisions to eject. The curves can be fitted by a Gaussian model with unequal variances; however, that model does not provide a ready interpretation of the shape of the obtained ROCs. HYPOTHESIS In an emergency, a pilot receives information from many parallel sources and will decide to eject if any one value from these sources exceeds the criterion for ejection. This process can be described by the extreme maximum value model. RESULTS When fitted to published asymmetrical ROC curves for the decision to eject, the extreme maximum value model with one parameter provides a better fit, according to Akaike and Baysean information criteria, than the unequal variance Gaussian model with two parameters. DISCUSSION In an emergency a pilot's decision to eject depends on whether any one value from several sources provides sufficiently strong evidence to exceed the criterion for ejection. A decision based on this policy is described by the extreme value model, which, therefore, offers a credible explanation of why the obtained ROCs are asymmetrical in shape.