measures of disease frequency

Question 1

2 measures of disease frequency

Answer 1

prevalence - existing cases
incidence - how many new cases develop in a defined population as time passes

Question 2

“bathtub analogy”

Answer 2

flow of water = incidence
level of water in the bath = prevalence
water can only leave the bath via death, recovery or emigration

Question 3

prevalence ≈

Answer 3

incidence rate x avg duration