Exhibit 4.

Influence on hospital referral region (HRR)–level variance of factors at the patient, physician, and HRR levels

Model	Model description	Fraction of variance in spending in the last 30 days of life attributed to HRRa	SD in spending across HRRs	Change in SD from prior model
1	No covariates	0.026	$2,833	__b
2	Demographic variables	0.023	2,646	−7%
3	Model 2 with patient clinical variables	0.020	2,461	−7
4a	Model 3 with HRR-level availability of services	0.008	1,509	−39
4b	Model 3 with physician beliefs	0.011	1,830	−26
4c	Model 3 with patient beliefs	0.021	2,496	1
5	All variables	0.004	1,020	−59c

SOURCE Authors’ analysis of data from patient surveys, medical records, physician surveys, and the Area Heath Resources Files. NOTE SD is standard deviation.

^aIntraclass correlation (ICC).

^bNot applicable.

^cChange from model 3.