Re:Slipping Away: Jo Aubin Has Alzheimer's. He's 38
by Phemist on Monday September 07, 2015 @07:56AM
(#10181075)
Except that you are not picked from the whole population at large, but from a subset of it. Namely the subset that (weakly) believes they have dementia. This changes the incidence rate (or likelihood function) probably by at least an order of magnitude.
[ Parent
| on HN ]
Re:Slipping Away: Jo Aubin Has Alzheimer's. He's 38
by kpmah on Monday September 07, 2015 @10:23AM
(#10181515)
You're right. You have to update the probability with all the knowledge you have. Although I would say self diagnosis has a very, very high false positive rate, and if you know you're a hypochondriac that would make the probability drop, plus we don't even have a test for this that is 90% accurate. I'm not sure the difference is an order of magnitude :)
I think my point stands that it doesn't make sense to test for extremely rare diseases because of a self diagnosis.