Microbial testing in food safety: effect of specificity and sensitivity on sampling plans - how does the OC curve move

Obviously the quality of test methods does have an impact on the performance of sampling plans. A low sensitivity means that actual positive samples are tested negative (i.e. false negatives) and moves the Operating Characteristic (OC) curve to the right. Values of sensitivity above 0.70 do not show large effects on the position of the OC curve. A low specificity means that actual negative samples are tested positive (i.e. false positives) and moves the OC curve to the left. The effect of the specificity of the testing method has a very large effect on the performance of a sampling plan, especially for sampling plans with higher numbers of samples. In those cases specificity should be much larger than 0.99 to have a reasonable performance.