Re:A blood test accurately diagnosed Alzheimer's 90% of the ...
by nrr on Saturday August 03, 2024 @09:45AM
(#41146586)
I think you may be close but likely for the wrong reasons. I had to sit down with this for a moment to feel comfortable with it.
If we take your 10% base rate to be disease prevalence, that gives us 100 sick and 900 well.
Of the 100 sick, something with 90% sensitivity should get me 90 true positive tests and 10 false negative tests.
Of the 900 well, I should expect to see for a test with 90% specificity, what, 80 false positives and 810 true negatives? if I did my arithmetic right?
If we take your 10% base rate to be disease prevalence, that gives us 100 sick and 900 well.
Of the 100 sick, something with 90% sensitivity should get me 90 true positive tests and 10 false negative tests.
Of the 900 well, I should expect to see for a test with 90% specificity, what, 80 false positives and 810 true negatives? if I did my arithmetic right?