doi:10.1016/j.jtcvs.2004.03.022 I f surgical performance—often measured by postoperative outcome of initial hospital stay—is monitored at all, the most common means is by risk-adjusted annual or semiannual audit. Observed occurrence of outcome measures (eg, in-hospital death and complications) as a proportion of cases performed is compared with expected performance using, for example, the Society of Thoracic Surgeons’ regression equations or EuroSCORE, which account for many aspects of case mix. Sometimes observed (O) and expected (E) proportions are subtracted, sometimes divided (O/E ratio); sometimes confidence limits of these comparisons are provided, and occasionally P values are given. Is this periodic, widespread, but rather coarse monitoring of surgical performance sufficient?