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Diagnostic test evaluation and comparison

Numbers of false positives to a test


This utility calculates the expected probability of numbers of false positive results to a test for a given sample size and test specificity, assuming the sample is from an uninfected population. It answers the question: For a given sample size and test specificity, and assuming that all animals are uninfected, what is the probability that there will be 1, 2, 3 etc false positives? . It also answers the related questions: What is the probability of x (1, 2, 3, etc) or more false positive results? and What is the probability of x (1, 2, 3, etc) or less false positive results?.

Inputs:

  • Test unit specificity; and
  • Sample size.

Outputs:

A table and plot of probabilities for each of the following:

  • the likely numbers of false positives (x);
  • less than or equal to x false positives; and;
  • greater than or equal to x false positives.