Uncertainty associated with microbiological
measurement

Understand the concepts associated with uncertainty in microbiological measurements and the importance of this in expressing analytical results.

No measurement is perfect. It has an uncertainty arising from many factors including errors and imperfect reproducibility. Ideally each measurement should be quoted with an indication of the uncertainty, often as a ± figure, so that decisions based on the measurement are fully informed. Microbiological testing laboratories are now being encouraged to express their results with an indication of uncertainty.

This document has been written to outline the concepts associated with determining the uncertainty associated with microbiological results and to try to explain the statistics associated with calculation of uncertainty. It uses a worked example based on plate counts derived from various food samples to illustrate data presentation and uncertainty calculations, with 'templates' for use in Excel and Minitab. The contents include:

• Summary
• Introduction
• Principles of uncertainty
• Application to microbiology
• Data analysis - results and discussion
• Conclusions
• Implications and further work
• References
• Appendix - worked example

Softcover - 27 pages