Table 6. Proportion of variance in total cost explained, by diagnosis-related group (DRG) splits, staging splits, and general linear model.

Adjacent DRG	Number of cases	DRG splits	Staging splits	Analytical model
		R2	R2	R2	F-values and significance
					Condition	Stage by condition	Unrelated comorbidity	Age
Biliary tract procedures	1265	.07	.11	.19	43.60*	16.27*	46.14*	14.89*
Cirrhosis and alcoholic hepatitis	299	10	.16	.18	2.38	12.62*	0.03	1.27
Diabetes mellitus	2290	.0001	.08	.09	10	45.44*	66.10*	2.15
Benign prostatic hypertrophy	370	.02	.11	.14	10	10.85*	27.29*	1.78

¹Insufficient degrees of freedom for this effect.

^*Significant at the 5-percent level.