Table III.

Intraobserver agreement

	X-ray	2D CT	3D CT	3D models
Consultants and registrars (n = 7)
kappa
Mean κ	0.45	0.41	0.43	0.60
Range of κ	0.32-0.63	0.10-0.64	0.36-0.53	0.45-0.89
95% CI	0.36-0.54	0.25-0.57	0.37-0.48	0.46-0.73
Agreement∗	Moderate	Moderate	Moderate	Moderate
Range of P values†	P = .016 to P < .0001	P = .201 to P < .0001	P = .004 to P < .0001	P = .0005 to P < .0001
Mean % agreement
%	70.5	65.6	65.5	75.0
95% CI	62.8-78.1	53.9-77.3	61.2-69.9	66.4-83.6
Number of images	30	30‡	30‡	30§
Consultants (n = 3)
kappa
Mean κ	0.46	0.45	0.39	0.69
Range of κ	0.42-0.48	0.33-0.56	0.36-0.44	0.51-0.89
Agreement	Moderate	Moderate	Moderate	Substantial
Mean % agreement	74.4	70.8	65.6	82.0
Registrars (n = 4)
kappa
Mean κ	0.44	0.37	0.45	0.52
Range of κ	0.32-0.63	0.10-0.64	0.40-0.53	0.45-0.60
Agreement	Moderate	Fair	Moderate	Moderate
Mean % agreement	67.5	61.7	65.5	69.8

2D, two-dimensional; 3D, three-dimensional; CI, confidence interval; CT, computed tomography.

^∗Agreement has been defined using the Landis and Koch criteria (Table I).²⁰

^†P value less than .05 shows that kappa was statistically significantly different from “0”. Range of P values assessing kappa for each observer.

^‡29 images for one observer

^§29 images for two observers.