Assessing cognitive estimation.

The Cognitive Estimation Test (CET) was devised in an attempt to quantify the tendency observed in patients with frontal lobe lesions to produce bizarre estimations in response to fairly simple questions, despite performing normally on standard intelligence tests. Several studies have been published where CET performance in patient groups has been examined. However, there is a paucity of adequate normative data. In the present study, representative normative data are provided from 150 healthy controls. CET performance was found to be moderately related to general intellectual ability, with females performing more poorly than males. The scale was examined psychometrically, and was found to be factorially impure, with poor internal reliability but adequate inter-rater reliability. Further revision of the CET is required in order to render it a psychometrically acceptable instrument.