Estimation of the POD function and the LOD of a qualitative microbiological measurement method.
Qualitative microbiological measurement methods in which the measurement results are either 0 (microorganism not detected) or 1 (microorganism detected) are discussed. The performance of such a measurement method is described by its probability of detection as a function of the contamination (CFU/g or CFU/mL) of the test material, or by the LOD(p), i.e., the contamination that is detected (measurement result 1) with a specified probability p. A complementary log-log model was used to statistically estimate these performance characteristics. An intralaboratory experiment for the detection of Listeria monocytogenes in various food matrixes illustrates the method. The estimate of LOD50% is compared with the Spearman-Kaerber method.
Wilrich
Cordula
C
Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12200 Berlin, Germany. wilrich@wiwiss.fu-berlin.de
Wilrich
Peter-Theodor
PT
D000465:Algorithms; D000818:Animals; D001681:Biological Assay / Q000592:standards*; D015169:Colony Count, Microbial; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000187:drug effects; D008828:Microbiological Techniques / Q000592:standards*; D008892:Milk / Q000382:microbiology; D015233:Models, Statistical; D015203:Reproducibility of Results; D013242:Sterilization