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