AOAC CASP Meeting Book
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The POD estimate is calculated as the number of positive outcomes divided by
the total number of trials.
Estimate the POD with a 95% confidence interval for the candidate method, the reference method and, if included, the presumptive and confirmed results. See
Annex C for details.
4.1.3.11.3
Difference of Probabilities of Detection (dPOD)
Difference of probabilities of detection is the difference between any two POD
values.
Estimate the dPODC as the difference between the candidate method and reference method POD values. Calculate the 95% confidence interval on the
dPODC.
dPODC = PODC – PODR
Estimate the dPODCP as the difference between the candidate presumptive result POD (PODCP) and the candidate confirmed result POD (PODCC) values. Calculate the 95% confidence interval on the dPODCP. See Annex C for details.
dPODCP = PODCP – PODCC
If the confidence interval of a dPOD does not contain zero, then the difference
is statistically significant at the 5% level.
4.1.3.11.4
Summary Data Tables
For all matrices and levels, use the summary table from Annex D.
4.1.3.11.5
Graph of Data
For each matrix, graph POD R , POD C , and dPOD by level with 95% confidence
intervals. See example in Annex E. 538 539 540 4.1.4 Robustness Study [Performance Tested Methods (PTM) or R 2 submissions only]
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4.1.4.1 Strain Selection
Robustness strains are prepared and analyzed as vegetative cells, spores or components thereof as applicable to the candidate method. One material is tested at
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