Figure 1. Relationship between incidence of epidural analgesia in each practitioner's patient population and each physician's cesarean section rate for dystocia. Each point represents the data for one obstetrician. There was no significant relationship (R²= 0.019, P = 0.156; parameter estimate for epidural analgesia: 0.071 [95% confidence interval -0.027, 0.169]). Weighting each obstetrician's data by the number of patients cared for during the study period did not strengthen the relationship (R²= 0.006, P = 0.422; parameter estimate: 0.04 [95% confidence interval:-0.0016, 0.14]).