HerdPlus: SeH and SpH for range of sample sizes and cut-points for given herd size
Calculate herd sensitivity (SeH) and herd specificity (SpH) for a range of sample sizes and cut-point numbers of reactors, for specified herd size, test sensitivity, test specificity and design prevalence. Also calculates:
- SeH values where SpH is constrained to be greater than a specified minimum value; and
- The sample size and cut-point for maximum SeH given constraints of the range of sample sizes and cut-points and specified minimum SpH and maximum SeH.
- Test sensitivity and specificity;
- Animal-level design prevalence (the hypothetical prevalence to be detected);
- Maximum desired SeH and minimum SpH;
- Specified herd/population size;
- Maximum and minimum sample sizes to be considered;
- Maximum and minimum cut-point number of reactors to classify a herd/flock as positive; 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:
- Tables and plots of SeH and SpH for combinations of sample size and cut-points;
- A table of SeH values corresponding to SpH values greater than or equal to the specified minimum SpH; and
- A summary of the sample size, cut-point and maximised SeH given the specified constraints on SeH and SpH.
Developed by Matthias Greiner and Evan Sergeant