Table 2.

Hierarchical Multilevel Models to Partition Percentage of Variance in 30-day Mortality at Surgeon and Hospital Level

	Null model	Controlling for patient characteristics	Controlling for patient characteristics, surgeon volume, hospital volume	Controlling for patient characteristics, surgeon volume, hospital volume, surgeon and hospital characteristics
2-level model (patient, surgeon)
Residual ICC (% variance) – surgeon	21.8%	-	-	-
2-level model (patient, hospital)
Residual ICC (% variance) – hospital	13.7%	-	-	-
3-level model (patient, surgeon, hospital)
Residual ICC (% variance) – surgeon	8.9%	9.4%	1.1%	0.4%
Residual ICC (% variance) – hospital	9.8%	9.1%	5.2%	3.9%