Daily Archives: 12/07/2021

OK, I refer you to another excellent post by John Dee entitled False Positive Refresher. In it he talks about the PCR test’s sensitivity (which is the nominal percentage of true cases it spots). A sensitivity of 80% means that if you test 100 sick people, it will miss 20 of them. More importantly, in this context, is the specificity (which is the nominal percentage of genuine negatives it spots). So a specificity of 99% means that if you do the test in 100 well people, it labels one as sick, ie as a false positive.