Figure 3.

Relation between mortality and volume of cases in surgery for repair of atrioventricular septal defect in children aged <1 year, 1991-5. r=estimated change (excluding data from Bristol) in odds of death for each extra case per year; p values are for a two sided test of the hypothesis of no association. Solid line shows the relation fitted by logistic regression, dashed lines show 95% confidence intervals (see appendix 2 for reasons for curved lines)