00:01
So we're giving this information about malagent cancer.
00:03
We're told that the prevalence rate is 1%, the false positive rates 10%, and correctly identifying maligency when subjects has cancer is 80%.
00:14
Well, with this information, we can try to find conditional probabilities, but right now it kind of just looks a little messy.
00:21
So i'm just going to assume that we have 1 ,000 subjects.
00:28
So assume 1 ,000 subjects.
00:36
With this 1 ,000 subjects, i can fill out.
00:39
A quick little table.
00:43
So this is the table we want to fill out.
00:45
We have positive tests or the magic cancer was indicated or a negative test maligent cancer is not indicated, the subject has cancer or the subject does not have cancer.
00:58
Well, if we're assuming, we have a thousand subjects, the prevalence rate is 1%.
01:04
So out of 1 ,000 subjects, 1 % of them will have the cancer.
01:13
There should be a total of 10 people that have cancer.
01:19
So that will also mean 99 people do not have cancer.
01:33
All right.
01:36
Well, out of those 10 people who have cancer, we know we have a false positive rate of 10%.
01:43
Or out of the 10 people who have cancer, we know correctly and then find maloney when the cancer has subject is 80%.
01:54
So we're going to take the 10 people and multiply that by 0 .8.
01:57
So we know that eight people are correctly identified.
02:02
So that eight people has the true positive.
02:10
So the remaining two had a false negative.
02:22
So out of the 990 that did not have cancer, there's a 10 % false positive.
02:28
So you'll take your 990, multiply that by 10 % of 99.
02:35
So we have 99 subjects who had positive tested.
02:39
But do not have cancer.
02:41
So this is our false positive...