Table 3.

Interobserver reliability across 12 observers

Classification	Coefficient	95% confidence interval
Primary classifications (A, B and C)	k F
Read 1	0.74	0.71 to 0.78
Read 2	0.73	0.69 to 0.76
All reads	0.74	0.71 to 0.76
Sub-classifications (A0-A4, B1-B2, C)	α k
Read 1	0.68	0.51 to 0.81
Read 2	0.65	0.45 to 0.80
All reads	0.67	0.53 to 0.77

α _k , Krippendorff’s alpha coefficient; k _F , Fleiss’s kappa coefficient