Table 1.

Distribution of the sample of private NHs affiliated to a chain.

	Initial Sample	Final Sample	NHs with Agreement (%)	Number of Provinces	Provincial Concentration (% of Top 3 NHs)
Total	921	642	63.86	49	45.02
No Big6	423	260	47.31	39	50.77
Big6	498	382	75.13	46	42.15
DomusVi	273	173	17.34	32	31.79
Ballesol	41	39	65.62	16	48.72
Amavir	35	34	100.00	8	82.35
Orpea	63	60	28.33	17	65.00
Vitalia	40	36	11.11	14	47.22
Sanitas	46	40	57.50	14	70.00