TABLE 3.

Extent of geographic clustering, as indicated by AI and PS statistics

Statistic	Observed value			Null value			P valuea
	Mean	Lower 95% CI	Upper 95% CI	Mean	Lower 95% CI	Upper 95% CI
Among countries (8 states)
AI	3.29	2.66	3.92	8.47	7.46	9.36	0.00
PS	25.71	24.00	27.00	54.62	51.28	57.87	0.00
Peru (n = 30) vs others
AI	1.51	0.96	2.05	4.50	3.58	5.48	0.00
PS	10.68	9.00	12.00	26.47	23.99	28.56	0.00
Brazil (n = 44) vs others
AI	2.21	1.80	2.60	5.45	4.35	6.49	0.00
PS	15.44	14.00	17.00	34.12	30.18	37.56	0.00
Colombia (n = 3) vs others
AI	0.62	0.32	0.87	0.59	0.27	0.89	0.55
PS	2.84	2.00	3.00	2.98	3.00	3.00	1.00
Venezuela (n = 4) vs others
AI	0.47	0.43	0.54	0.82	0.51	1.15	0.03
PS	3.01	3.00	3.00	3.98	3.87	4.00	0.01
Trinidad (n = 13) vs mainland
AI	0.18	0.01	0.51	2.43	1.76	3.01	0.00
PS	5.68	5.00	6.00	12.53	11.48	13.00	0.00
Panama (n = 3) vs others
AI	0.06	0.01	0.26	0.60	0.30	0.90	0.00
PS	2.00	2.00	2.00	2.99	2.98	3.00	0.00
Ecuador (n = 3) vs others
AI	0.83	0.58	0.97	0.61	0.29	0.92	0.91
PS	3.00	3.00	3.00	2.98	2.97	3.00	1.00
Bolivia (n = 6) vs others
AI	1.18	0.74	1.61	1.57	1.10	2.08	0.10
PS	7.32	6.00	8.00	7.89	7.00	8.00	0.04

^aValues in bold indicate statistical significance.