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PDA Journal Case Study: Statistical Testing and TR33

Posted by Rapid Micro Biosystems on October 7, 2015

In the July/August 2015 issue of the PDA Journal of Pharmaceutical Science and Technology, Thomas Murphy, Julie Schwedock, Kham Nguyen, Anna Mills, and David Jones published the case study, “Evaluation of PDA Technical Report No 33. Statistical Testing Recommendations for a Rapid Microbiological Method Case Study.”  The peer-reviewed study applies statistical methods to, “analyze accuracy, precision, ruggedness, and equivalence data obtained using a rapid microbiological method system being validated for water bioburden testing. The case study demonstrates that the statistical methods described in the PDA Technical Report No. 33 chapter can be successfully applied to rapid microbiological method data sets and give the same comparability results for similarity or difference as the standard method.”

The case study tested the general application of the statistical tests suggested in TR33 using results obtained during an evaluation of the Growth Direct™ System. The study used the evaluation approach for the Growth Direct System as defined in section 3.7 Automated Methods in TR33 as well as the methods and acceptance criteria of section 5.

Using the statistical analysis recommended in the TR33, the study was able to show, “good equivalence between the Growth Direct Method and the Plate Count method.”  The study went on to note that, “the statistical methods suggested in the new TR33 document were generally found to be acceptable to the successful validation of the Growth Direct System.  The study did point out, “That care should be taken in applying statistical methods when average CFU values are very low.

To download a copy of the July/August Issue of the PDA Journal (membership/purchase required), visit à