HerdPlus: SeH and SpH for optimised sample sizes for range of herd sizes
Calculate optimised sample size and cut-point 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 cut-point 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.
- 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;
- Animal-level design prevalence (only required if option for specified design prevalence 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 cut-points 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 cut-point against herd size.
Developed by Matthias Greiner and Evan Sergeant