Herd-level sensitivity for testing in a finite population

Inputs Input Values

This utility estimates the probability of detecting disease (herd-sensitivity) in a finite population, if it is present at the specified design prevalence, assuming a test of known sensitivity and 100% specificity and that all samples have a negative test result. These analyses use an approximation of the hypergeometric distribution (MacDiarmid, SC (1988). NZ Vet J, 36:39-42). Because test specificity is assumed to be 100%, herd-specificity for these calculations is also 100%.

Inputs are the sample size tested, the population size, test sensitivity and the design (target) prevalence.

Outputs are:

• the herd-level sensitivity for the given sample size, population size, test sensitivity and design prevalence; and
• a table of herd-sensitivity values for a range of design prevalence and sample size values for the specified population size.