AOAC-RI ERP Book Micro Jan 19 2017

OMAMAN-35 B: Collaborative Study Protocol ERP USE ONLY January 2017

3M MDA2 E. coli O157:H7 Collaborative Study

May 2016

OMA-2016-May-XXXX

1 c) Copies of all related test results (data sheets and confirmation results) should be retained by the 2 collaborating labs for a minimum of one year. 5 6 a) The resulting data will be analyzed by two different calculations: probability of detection (POD). 7 8 b) Probability of Detection (POD) - POD is the proportion of positive analytical outcomes for a 9 qualitative method for a given matrix at a given analyte level or concentration. POD is 10 concentration dependent. Please see the revised microbiology guidelines 1 for complete analysis 11 information on POD calculations. 3 4 5) Analyzing Raw Data

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a) Calculate:

(1) Estimate of repeatability - standard deviation (s r )

(2) Determine POD values for each matrix and concentration - the number of positive

outcomes divided by the total number of trials.

(3) Estimate of reproducibility – standard deviation of the laboratory POD values (s POD ) and

confidence intervals.

(4) Cross laboratory probability of detection (LPOD) – LPODs by matrix and concentration with 95% confidence intervals for candidate method (presumptive and confirmed)

results.

(5) Difference of cross-laboratory probability of detection (dLPOD) – difference probability

of detection is the difference between any two LPOD values.

(a) Estimate dLPOD C

as the difference between the candidate and reference LPOD

values, include CIs.

(b) Estimate dLPOD CP

as the difference between the presumptive and confirmed LPOD

values, include CIs.

(c) If the CI of a dLPOD does not contain zero then the difference is statistically

significant .

(6) For each matrix, graph POD R

, LPOD C

and dLPOD C

by level with 95% confidence intervals.

AOAC Research Institute Expert Review Panel Use Only

6) Appendices

a) Instructions to Collaborators b) Test Portion Data Report Forms

c) Study Materials

d) Flow Diagram – raw ground beef (325 g)

Appendix 8.1

Instructions to Collaborators

General Instructions about Collaborative Studies

1 AOAC INTERNATIONAL Methods Committee Guidelines for Validation of Microbiological Methods for Food and Environmental Surfaces (pre-publication document, 2012) Sharon Brunelle, Robert LaBudde, Maria Nelson, and Paul Wehling

DRAFT DOCUMENT

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