The screening test for Crohn's has a sensitivity of 80% and a specificity of 90.2%.

Question

The screening test for Crohn's has a sensitivity of 80% and a specificity of 90.2%. Assume that this test is applied to the group of approximately 3.3 million Americans who suffer from symptoms that are very similar to those of Crohn's. Suppose also that all of the 0.58 million Crohn's sufferers belong to this group.

Fill in the following table based on this group of 3.3 million. (Write your answers in millions and round to two decimal places.)

Has diseaseDoes not have diseaseTotals
Test positive (millions)
Test negative (millions)
Totals

Answer 1

Sensitivity of 80% means the percentage of Crohn's sufferers whose test are positive is 80%.

Specificity of 90.2% means percentage of non-Crohn's sufferers whose test are negative is 90.2%.

has disease, no Disease, total

Test + 0.58*0.8=0.46, 2.72*0.08=0.22, 0.68

Test - 0.58*0.2=0.12, 2.72*0.92=2.5, 2.62

total 0.58, 3.3-0.58=2.72, 3.3