The premises are as obvious as they are straightforward. Ask a relative of the traumatic brain injured patient to rate that patient’s cognitive capacities in order to compare the more objective report with the patient’s self-report. Significant differences between proxy and patient reports are routinely held as prima facie evidence of dysexecutive function—a crucial indicator of the generally poor rehabilitation prospects for these patients. The paper by Chan and Bode in this issue of J Neurol Neurosurg Psychiatry1 reports the nature and extent of the differences between patient and proxy ratings for 92 postconcussive patients (see page 86). Usual psychometric procedures use the total score (counts) of Likert-type …