Mathematical treatment of plates with colony counts outside the acceptable range.
The exclusion of plate counts outside of an acceptable range can bias the estimation of concentration. If these plates are too numerous to count (TNTC), then their microbes may be inhibited. If inhibition of the microbes on a plate is suspected, then its count may be best treated as a lower bound. When these lower bounds replace counts for some plates, the estimate and confidence interval must be calculated accordingly. Also, a measure of unusualness for plate counts is discussed.
Blodgett
Robert J
RJ
Center for Food Safety and Applied Nutrition, Food and Drug Administration, Room 2D-011, HFS-012, 5100 Paint Branch Parkway, College Park, MD 20740, USA. robert.blodgett@fda.hhs.gov
D001419:Bacteria / Q000254:growth & development*; D015169:Colony Count, Microbial / Q000379:methods* / Q000592:standards*; D016001:Confidence Intervals; D008433:Mathematics; D011336:Probability