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"It correctly identified when cancer was present in 51.5% of cases, across all stages of the disease, and wrongly detected cancer in only 0.5% of cases." Doesn
by starkd 5y ago
"It correctly identified when cancer was present in 51.5% of cases, across all stages of the disease, and wrongly detected cancer in only 0.5% of cases."
Doesn't this seem kind of low? Just a bit better than a coin flip. Of course, it rises to 65% and 87% for certain circumstances and the false positive rate is low, but it seems like a lot of cancers could fail to be detected and give a false assurance patients are cancer free. When symptoms emerge later they may be less concerned with getting it checked out. Is this in line with standard performance of tests?
- phunehehe0 5y agoThis is much better than a coin flip. A coin flip would give about 50% true positive rate (which is about the same as the test), but it would also give about 50% false positive rate. To put it in perspective, imagine 10 people have cancer in a population of 1000 (a rate of 10% which is too high compared to what I think the real number should be). The test would fail to identify 5 of the people with cancer, and it would say that 5 of the people without cancer have cancer. So overall it would misidentify 10 people. The coin flip would misidentify 500 people. Amusingly in this example if you have a "test" that just says nobody has cancer it would also misidentify only 10 people :) I think this is why they are reporting true positive rate and false positive rate.
- starkd 5y agoI see. I guess its more important to keep false positives low than increase detection accuracy. Thank you very much for this explanation.