Question

A certain disease has an incidence rate of 0.4%. If the false negative rate is 7% and the false positive rate is 5%, compute the probability that a person who tests positive actually has the disease.

Answer 1

where do you get the .95 from?

Explanation:

Answer 2

The incidence rate is = 0.4% or 0.004

The false negative rate is = 7% or 0.007

The false positive rate is = 5% or 0.005

The probability is

0.05*(1-0.004) + 0.95*0.004

= 0.0498 + 0.0038 = 0.0536

Probability that a person who tests positive actually has the disease would be represented as:

Let the probability be represented by = p

p * 0.0536 = 0.95 * 0.004

p = 0.0038/0.0536

p = 0.0708

Hence, probability is 0.0708