Table 2.

Kappa values for inter- and intra-observer variation for the AO classification

	Inter-observer						Intra-observer
	A	B	C	D	E	F
A		0.56	0.58	0.24	0.51	0.47	0.51
B			0.50	0.34	0.47	0.43	0.61
C				0.34	0.41	0.45	0.60
D					0.35	0.36	0.37
E						0.43	0.54
F							0.58
Mean κ value for each observer	0.47	0.46	0.46	0.33	0.43	0.43
Mean κ value for all observers	0.43						0.53

A and B were consultants, C and D were SpRs, E and F were research fellows.