This utility calculates the sample size required to achieve a desired level of confidence of population freedom. Can be applied at the cluster (herd/flock) level or population level. If applied at the cluster level, sensitivity and design prevalence are unit (animal) level values, whereas if applied at the population level, sensitivity and design prevalence are cluster level values.
Enter test sensitivity if the target is a cluster level freedom or cluster-sensitivity if the target is a system or population level freedom. If population size is entered the hypergeometric approximation is used, otherwise the calculation is based on the binomial distribution.
A sample size of "n>N" indicates that it is not possible to achieve the desired level of confidence by testing the entire population. This most commonly occurs with low design prevalence and poor unit sensitivity of the test in a finite population.