Georgiadis Marios P, Johnson Wesley O, Gardner Ian A
Department of Animal Production, Ichthyology, Ecology and Environmental Protection, School of Veterinary Medicine, Aristotle University of Thessaloniki, GR 54124 Thessaloniki, Greece.
Prev Vet Med. 2005 Sep 30;71(1-2):1-10. doi: 10.1016/j.prevetmed.2005.04.004.
We developed an Excel spreadsheet template (available at http://www.epi.ucdavis.edu/diagnostictests/) to calculate sample sizes to estimate sensitivity and specificity with desired precision in the absence of a gold standard. Calculations are predicated on the use of two conditionally independent tests for screening animals from two populations and are based on the methods of Hui and Walter(1980). Sample size calculations rely on asymptotic normality of maximum likelihood (ML) estimates of parameters. Spreadsheets for calculating standard errors for the parameter estimates and for providing ML estimates using cross-tabulated data also are included. An example of application of the methods to bovine paratuberculosis is presented.
