Question

Early diagnosis and treatment of malaria are necessary components in the control of malaria. The gold-standard light microscopy test has high sensitivity but is a relatively time-consuming procedure especially during epidemics and in areas of high concentration. A new Cyscope fluorescence microscopy test has been developed and gives results in less than 10 minutes. The test has a specificity of 98.92% and a sensitivity of 95.48%.

Required:
a. What proportion of the people who test positive for Malaria would we expect to actually have the disease?
b. What proportion of people who test positive for Malaria will not have the disease?

Answer 1

a) 0.9548

b) 0.0452

Explanation:

Specificity of test:

The specificity of a test is the true negative rate, that is, the proportion of people without the disease that test negative.

Sensitivity of test:

The sensitivity of a test is the true positive rate, which is the proportion of people with the disease that test positive.

a. What proportion of the people who test positive for Malaria would we expect to actually have the disease?

This is the sensitivity of the test, which is of 95.48%, so the proportion if 0.9548.

b. What proportion of people who test positive for Malaria will not have the disease?

True positive rate is of 95.48%.

1 - 0.9548 = 0.0452

So the proportion of people who test positive for Malaria will not have the disease is 0.0452.