# MEDICAL TESTS. Medical tests are used to indicate whether a person has a particular disease

August 30, 2017

Question
MEDICAL TESTS. Medical tests are used to indicate whether a person has a particular disease.

The sensitivity of a test is the probability that a person having the disease will test positive (indicating the person has the disease, i.e., it’s the probability the test will pick up the fact that a person has the disease).

The specificity of a test is the probability that a person not having the disease will test negative.

A test for a certain disease has been in use for many years. Based on the “track record” of this test, its sensitivity is 0.934 and its specificity is 0.968. Finally, in the population, 1 in 500 people has the disease.

What is the probability that a person who tests positive actually has the disease?
What value would the specificity of the test have to have in order for the probability to exceed 0.5 that a person who tests positive actually has the disease?

Get a 30 % discount on an order above \$ 100
Use the following coupon code:
RESEARCH
Positive SSL