In the signal detection paradigm, the non-parametric index of sensitivity A′, as first
introduced by Pollack and Norman (1964), is a popular alternative to the more traditional d′
measure of sensitivity. Smith (1995) clarified a confusion about the interpretation of A′ in
relation to the area beneath proper receiver operating characteristic (ROC) curves, and
provided a formula (which he called A′′) for this commonly held interpretation. However,
he made an error in his calculations. Here, we rectify this error by providing the correct …

In the signal detection paradigm, the non-parametric index of sensitivity A′, as first
introduced by Pollack and Norman (1964), is a popular alternative to the more traditional d′
measure of sensitivity. Smith (1995) clarified a confusion about the interpretation of A′ in
relation to the area beneath proper receiver operating characteristic (ROC) curves, and
provided a formula (which he called A′′) for this commonly held interpretation. However,
he made an error in his calculations. Here, we rectify this error by providing the correct …