Sample size for demonstration of freedom (detection of disease) using pooled testing

Input Values

  

This utility calcuates the number of pools required to be tested to provide a desired probability of detecting disease ( herd-sensitivity) at the specified design prevalence, for a large (infinite) population, using pooled testing and assuming a fixed pool size and a test of known sensitivity and 100% specificity. These analyses are an adaptation of the method from Cowling et el. (1999) (Prev Vet Med, 39:211-225), assuming known test sensitivity, perfect test specificity and 1 or more pools positive to declare a population infected (i.e. to be recognised as free there must be zero positive pools).

Inputs are the pool size used, pool-level test sensitivity, desired herd-sensitivity and design (target) prevalence. Test sensitivity is measured at the pool level (i.e. the probability that a pool will test positively if it represents one or more infected animals).

Outputs are:

  • the number of pools of the specified size that must be tested to achieve the desired herd-sensitivity for the given design prevalence;
  • a table and graph of various pool sizes and corresponding numbers of pools that must be tested to provide the desired herd-sensitivity for a range of design prevalence values, assuming the same test sensitivity applies to all pool sizes.

Size of pools:
Test Sensitivity:
Desired herd-sensitivity:
Design (target) prevalence:

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