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Efficient Sample Size Calculator

This model estimates the sample size needed to declare a population free from disesae, explicitly accounting for biological clusterings within the overall population. Users can select simple random sampling, high-harvest, or two-stage cluster sampling schemes.

Geographical Scale

  • Biological population of interest (N)

Required Data

  • None

Suggested Data

  • None

User Inputs

  • Total population size estimate
  • Average cluster size
  • Whether cluster sizes are fixed or random
  • Correlation of disease status within cluster
  • Diagnostic test sensitivity

Outputs

  • The number of animals that need to be tested to have high probability (95%) that disease prevalence in the overall population is at or below 1% or 2%.

graph of sample size vs probability of freedom from disease at a given prevalence

Example of model output showing sample size required to substantiate disease prevalence below 1% and 2% prevalence.

More information