Table 2.

Cross-Classification of Right and Left Eyes for Stage of ROP.

	Right Eye Stage
Left Eye Stage	0	1 or 2	≥3	Total
0	584 (49.0%)	30 (2.5%)	6 (0.6%)	620 (52.1%)
1 or 2	65 (5.5%)	110 (9.2%)	41 (3.4%)	216 (18.1%)
≥3	9 (0.8%)	52 (4.4%)	294 (24.7%)	355 (29.8%)
Total	658 (55.2%)	192 (16.1%)	341 (28.6%)	1191 (100%)

Percent exact agreement is 49.0% + 9.2% + 24.7% = 83.0%.

κ is (83.0%–40.2%)/(1–40.2%) = 0.71; 95% CI is (0.68, 0.75).

κ_w = 0.86. 95% CI of (0.85, 0.88), calculated using squared error weights and the large sample variance from Fleiss et al.⁴

Data from table 1 of the publication by Ying et al.¹