Table 3.

Observer agreement: kappa statistics (95% confidence intervals)

Radiographic features	Davies 1996 [10]	Simpson 1974 [14]	Coakley 1996 [8]	Kramer 1992 [12]	Crain 1991 [9]	McCarthy 1981 [15]
Inter-observer variation
Consolidation	0.79
Pneumonia				0.46 (0.34–0.58) 0.47 (0.35–0.60)
Collapse/consolidation		0.83 (0.72–0.94)
Collapse/atelectasis	0.78
Hyperinflation/air trapping	0.83	0.78 (0.67–0.89)
Peribronchial/ bronchial wall thickening	0.55	0.55 (0.44–0.66)	0.43 (0.25–0.61)
Perihilar linear opacities	0.82
Abnormal					0.61 (0.48–0.74)
Bacterial vs. viral etiology						0.27–0.38
Intra-observer variation
Consolidation	0.91
Collapse/atelectasis	0.86
Hyperinflation/air trapping	0.85
Peribronchial /bronchial wall thickening	0.76
Perihilar linear opacities	0.87

^aTwo observer pairs