The ratings given to job applicants in an assessment centre (AC) will be influenced both by an assessor's sensitivity to the evidence of suitability provided by the applicants, and by whether the assessor has a liberal or a conservative rating tendency. In this study we explore the usefulness of signal detection methodology for evaluating and comparing both aspects of performance. A group of eight managerial assessors in a real-world AC rated 195 applicants for retail sales positions. The sensitivity and response bias of assessors was evaluated using receiver operating characteristic (ROC) analyses, and their performance was evaluated by means of critical operating characteristic (COC) analyses. RscorePlus software (Harvey, 2002) was used for these purposes. We conclude that, in this and similar organizational contexts, such analyses are potentially useful for estimating and comparing the performances of assessors, thereby highlighting the need for, and subsequently evaluating the effectiveness of, any remedial intervention.