Gamma is a Measure of the Accuracy of Predicting Performance on One Item Relative to Another Item, not of the Absolute Performance of an Individual Item Comments on Schraw.

The recent paper by Schraw (Measures of feeling-of-knowing accuracy: a new look at an old problem. Applied Cognitive Psychology, 1995, 9, 321-332) is flawed by several inaccuracies and by Schraw's failure to distinguish between two fundamentally different aspects of the accuracy of metacognitive predictions: (1) calibration (aka absolute accuracy, defined in terms of whether the predicted value assigned to a single item is followed by the occurrence of that value on the criterion test), and (2) resolution (aka relative accuracy, defined in terms of whether the predicted performance on one item relative to another item is followed by the occurrence of that ordering of the two items on the criterion test). Because of these (and other) problems, his recommendations seem misleading and counterproductive. [ABSTRACT FROM AUTHOR]