Sample size determination for estimation of the accuracy of two conditionally independent tests in the absence of a gold standard.
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.
Georgiadis
Marios P
MP
Department of Animal Production, Ichthyology, Ecology and Environmental Protection, School of Veterinary Medicine, Aristotle University of Thessaloniki, GR 54124 Thessaloniki, Greece. marios@vet.auth.gr
Johnson
Wesley O
WO
Gardner
Ian A
IA
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D002417:Cattle; D003718:Denmark / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D008892:Milk / Q000276:immunology; D015233:Models, Statistical; D009162:Mycobacterium avium / Q000276:immunology / Q000302:isolation & purification; D010283:Paratuberculosis / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D018401:Sample Size; D012680:Sensitivity and Specificity
D000907:Antibodies, Bacterial