Exam 3: True and Apparent Prevalence

Question 1

What is prevalence?

Answer 1

The proportion of cases of disease within a population

Question 2

What are the 2 major sources of error?

Answer 2

The error (or uncertainty) associated with sampling, which we address by calculating a confidence interval
Misclassification error when using a diagnostic test, but error can be adjusted for in this case

Question 3

How do you calculate true prevalence?

Answer 3

(AP + Sp - 1) / (Se + Sp -1)

Question 4

How can you check a true prevalence calculation?

Answer 4

By constructing a 2x2 table, applying test Sn and Sp and calculating the number of positive tests

Question 5

If a diagnostic test does not miscalculate anything with a 100% sensitivity, 100% specificity, and 10% AP, what is true prevalence?

Answer 5

The same as apparent prevalence