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Table 1 Estimates for use in true prevalence calculation

From: Analysis of Johne’s disease ELISA status and associated performance parameters in Irish dairy cows

 

Estimates of posterior distributions

Beta distribution

  

Alpha

Beta

Animal Prevalence

0.033 (0.072)a

5.2021

124.1336

Sensitivity

0.41 (0.587)a

9.9689

13.5179

Specificity

0.99 (0.47)a

4.0322

1.0306

  1. The online epidemiological calculator (Epitools) used to calculate true prevalence requires prior estimates of the true prevalence and test sensitivity and specificity, based on previous data or expert knowledge. These estimates are made as Beta probability distributions, with parameters alpha and beta. Alpha and beta can be calculated provided estimates of the mode and 5 or 95 % confidence limits are available from expert opinion
  2. Initial values represent the mode, with the value in brackets representing either the 5th or 95th percentile
  3. aWhen the estimated value was between 0 and 0.5 the 95th percentile was chosen, and when the estimate was between 0.5 and 1 the 5th percentile was chosen
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BMC Veterinary Research

ISSN: 1746-6148

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