Figure 7

Bland-Altman plot comparing agreement between two methods of gestational age assessment, Ballard examination and best obstetric estimate. The difference between the two methods (Ballard minus best obstetric estimate) is plotted on the y-axis against the mean of the two methods on the x-axis. The identity line at y=0 represents values where the two methods yielded the same estimate of gestational age. The bias (the average difference between the two methods) is plotted as a solid line and the 95% limits of agreement represented by the dashed lines.