Table.

Percentage missing data and reliability scores for nine participating surgical centres which submitted mortality data for coronary artery bypass surgery for the 12 month retrospective phase and the five month prospective phase. Values are means (standard errors)

	Retrospective phase				Prospective phase
	% missing data elements	κ Coefficient	Centre reliability score		% missing data elements	κ Coefficient	Centre reliability score
Submitted data	24.96 (0.09)	0.67 (0.11)	0.44 (0.17)		9.33 (0.08)	0.78 (0.06)	0.53 (0.15)
Re-abstracted data	1.81 (0.06)				4.04 (0.05)