Micro December 2018

11/19/2018

OFFICIAL METHODS of ANALYSIS COLLABORATIVE STUDY PROTOCOL REVIEW FORM

Have appropriate statistics been calculated correctly? * Quantitative Qualitative Is the table of parameter estimates in AOAC format? * Yes No

Are the inferences/conclusions in line with the statistical parameter estimates? * Yes No

Do the appropriate statistics (or reference to table) appear immediately beneath the title/ applicability of the method? * Yes No

Is the table presented in AOAC format? * Yes No

Does the repeatibility, reproducibility, sensititivity and HORRAT values appear reasonable given the matrix, analyte and levels? * Yes No

GENERAL COMMENTS ABOUT THE METHOD * A practical and resource saving method for enumeration of E. coli and coliform with faster turn-around- time, for which the industry is looking. The results should be less impacted due to simple procedure involved in comparison with current reference methods. It is recommended for the company to propose a countable range for Petrifilm, such as 10 – 100, as that in the reference method (25 – 250). It seems that there is a chance when the bacterial concentration has to be estimated from Petrifilm in decimal dilution using counts of <20, where the data follow Poisson distribution, i.e. the estimated mean = variance and are a bit out of the quantification range. The bacterial enumeration estimated from low number will definitely affect the interpretation of a quantitative result. Or the company regards all the results from Petrifilm as estimate.

Are there any concerns regarding the safety of the method (if necessary, refer to the review from the Safety Advisor)? * No.

Are there any concerns regarding the data manipulation, data tables or statistical analyses (if necessary, refer to the review from the Statistics Advisor)? *

https://form.jotform.com/AOACINT/RIStatsReview

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