

Calculate optimised sample size and cutpoint and resulting
herd sensitivity (SeH) and herd specificity (SpH) for a specified
range of herd sizes, test sensitivity, test specificity and design prevalence.
Design prevalence can be specified as a fixed value, or as the equivalent of one animal per herd.
Sample size and cutpoint are constrained to provide SeH less than or equal to
a specified maximum value and SpH greater than a specified minimum value.
Sample sizes are also constrained to be no more than the specified
proportion of herd size.
Inputs include:
 Test sensitivity and specificity;
 Maximum desired SeH and minimum SpH;
 Maximum sample size relative to herd size;
 Specified range of herd/population sizes;
 Mode of setting design prevalence, either as a specified value or as a
proportion of herd size;
 Animallevel design prevalence (only required if option for specified
design prevalence s selected); and
 The desired precision of results (number of digits to be displayed after the decimal point).
Results are calculated using the HerdPlus method (Greiner 2006?) and include:
 Table of optimised sample sizes and cutpoints and corresponding SeH and SpH
values for combinations herd sizes in specified range; and
 Plot of SeH and SpH values for optimised sample size and cutpoint against herd size. and
Acknowledgement:Developed by Matthias Greiner and Evan Sergeant
