Table 4

CSU	Hayward
	Statistics	Department

Table 4: Gibbs Estimates of Prevalence From 10,000 Simulated Values After Burn-In
(Data: 49 positive tests among 1000 units of blood)

Beta Prior
On Prevalence Simulated Values of p Gibbs Interval Estimate

Mean Median 2.5% 97.5%

(a) a = 2, b = 50 2.05%
2.09%
2.08%
2.07%
2.07% 2.03%
2.06%
2.05%
2.04%
2.04% (0.85%,
(0.92%,
(0.85%,
(0.87%,
(0.86%, 3.45%)
3.48%)
3.52%)
3.47%)
3.46%)

(b) a = 2, b = 20 2.18% 2.15% (0.94%, 3.61%)

(c) a = 1, b = 1 2.05% 2.02% (0.75%, 3.56%)

(d) a = 7, b = 5 2.23% 3.20% (1.90%, 4.76%)

None (Sec. 2) 1.98% (0.58%, 3.38%)

Beta Prior On Prevalence	Simulated Values of p		Gibbs Interval Estimate
Beta Prior On Prevalence	Mean	Median	2.5%	97.5%
(a) a = 2, b = 50	2.05% 2.09% 2.08% 2.07% 2.07%	2.03% 2.06% 2.05% 2.04% 2.04%	(0.85%, (0.92%, (0.85%, (0.87%, (0.86%,	3.45%) 3.48%) 3.52%) 3.47%) 3.46%)
(b) a = 2, b = 20	2.18%	2.15%	(0.94%,	3.61%)
(c) a = 1, b = 1	2.05%	2.02%	(0.75%,	3.56%)
(d) a = 7, b = 5	2.23%	3.20%	(1.90%,	4.76%)
None (Sec. 2)	1.98%		(0.58%,	3.38%)