LIKELIHOOD-RATIO DECISION STRATEGY FOR INDEPENDENT OBSERVATIONS IN THE SAME-DIFFERENT TASK - AN APPROXIMATION TO THE DETECTION-THEORETIC MODEL

An optimal decision strategy for deciding whether two things are the s ame or different is to adopt a likelihood-ratio criterion. The paramet ric equations for the receiver operating characteristic (ROC) based on the likelihood-ratio strategy when observations are independent are c omplicated; they require the numerical evaluation of a double integral . An approximation to the parametric equations for the likelihood-rati o strategy was developed. This approximation takes the form of a pair of equations that describe ROCs virtually indistinguishable from those of the full model.