TABLE 4.

Precision of determination of the time of Campylobacter introduction into a flock of 20,000 broilers, with different sample sizes and sampling intervals^a

Sample size	90% interval of estimation error
	β unknownb for sampling interval		β known (β = 1.04) for sampling interval
	1 day	3 days	1 day	3 days	7 days	14 days
10	−2.91, 4.42	−4.49, 3.97b	−1.13, 2.93	−1.31, 3.05	−1.72, 3.25	−3.71, 4.84
20	−2.13, 3.62	−3.04, 4.16b	−1.08, 2.88	−1.19, 2.94	−1.43, 3.11	−3.08, 4.34
60	−1.46, 3.09	−1.97, 3.70	−1.05, 2.87	−1.08, 2.89	−1.17, 2.91	−2.17, 3.68

^aDenoted are the 90% intervals of the estimated introduction times of 10,000 simulated outbreaks starting on day zero.

^bWith β unknown, the introduction time could not be estimated for sampling intervals of 7 or 14 days, in only 69% of the cases with 10 samples every 3 days, and in only 90% of the cases with 20 samples every 3 days.