Table 2:

Intra-observer concordance of pathologists’ interpretations of STAS and artifact in first and second rounds of evaluation

STAS	FS % Agreement	Kappa	FSP % Agreement	Kappa	NFP % Agreement	Kappa
Observer 1	81	0.508	79	0.567	73	0.488
Observer 2	82	0.554	81	0.455	86	0.713
Observer 3	78	0.531	83	0.649	91	0.816
Observer 4	83	0.651	91	0.819	82	0.648
Observer 5	88	0.748	88	0.737	74	0.443
Mean Intra-observer Concordance (%) (95% CI)	82.4 (79.2 – 85.6)		84.4 (78.7 – 90.1)		81.2 (75.5 – 86.9)
Mean Cohen’s Kappa ± SE		0.598 ± 0.100		0.654 ± 0.142		0.622 ± 0.155
Artifact	FS % Agreement	Kappa	FSP % Agreement	Kappa	NFP % Agreement	Kappa
Observer 1	63	0.286	69	0.389	75	0.399
Observer 2	73	0.460	79	0.561	82	0.579
Observer 3	65	0.314	72	0.431	74	0.470
Observer 4	77	0.419	81	0.487	72	0.451
Observer 5	77	0.532	81	0.617	70	0.396
Mean Intra-observer Concordance (%) (95% CI)	71.0 (62.8 – 79.2)		76.4 (68.2 – 84.6)		74.6 (66.4 – 82.3)
Mean Cohen’s Kappa ± SE		0.402 ± 0.102		0.497 ± 0. 093		0.459 ± 0.074

FS: frozen section; FSP: frozen section permanent; NFP: non-frozen section permanent; CI: confident interval