Figure 4. Bland-Altman plots of ultrastructural visibility by still picture sonograms according to observer competence and nerve size.

a, experts and large nerves; b, experts and small nerves; c, trainees and large nerves; d trainees and small nerves. X-axis employs mean values of the Vienna scale, while the Y-axis employs observer differences of the Vienna scale. For interpretation of these results, see text.