I absolutely understand this situation. Been there, done that, got the Post-It note which explains the concept in Rubix-code and lives permanently in my notebook.
You’ve got your p(can+|mam+)=(p[mam+|can+]p[can+])/p(mam+). In numbers, that’s .8(eighty percent of 1%,) divided by 9.5(9.5% of 100%) plus that same .8. What you’re doing, I think, is omitting to recall that the eighty percent of women with cancer who test positive compromise .8% of all the women who get tested.
Also, it shook me up like nobody’s business that the percentage of women without cancer who tested positive kept switching between problems, between 9.5 and 9.6! (I’m easily shaken.)
The error is pretty basic, but it is not stupid because you asked for help. The only stupid question is the one which is not asked. This is a common statement, but a true one and I mean it.
I absolutely understand this situation. Been there, done that, got the Post-It note which explains the concept in Rubix-code and lives permanently in my notebook.
You’ve got your p(can+|mam+)=(p[mam+|can+]p[can+])/p(mam+). In numbers, that’s .8(eighty percent of 1%,) divided by 9.5(9.5% of 100%) plus that same .8. What you’re doing, I think, is omitting to recall that the eighty percent of women with cancer who test positive compromise .8% of all the women who get tested.
Also, it shook me up like nobody’s business that the percentage of women without cancer who tested positive kept switching between problems, between 9.5 and 9.6! (I’m easily shaken.)
The error is pretty basic, but it is not stupid because you asked for help. The only stupid question is the one which is not asked. This is a common statement, but a true one and I mean it.