4 ms·
This 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
by phunehehe0 5y ago
This 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.