Table 1.

Ratios of poorest to least poor (or richest) subpopulations for community effectiveness: the differential “staircase” effect. Values are percentages unless otherwise indicated

		Modifiers of efficacy
	Efficacy	Access	Diagnostic accuracy	Provider compliance	Consumer adherence	Community effectiveness	Least poor (richest):poorest equity effectiveness ratio
Treated bed nets for under-five mortality due to malaria
Least poor	20	75	95	90	60	7.7	1.4
Poorest	20	43	95	80	85	5.6
Arthroplasty for disability due to osteoarthritis
Richest	86	83	50	98	36	12.6	1.6
Poorest	86	76	43	98	28	7.7

^*Community effectiveness is the product of the efficacy modifiers of access, diagnostic accuracy, compliance of providers, and adherence of consumers.