lecture 5 -dz occurances

Question 1

Prevalence

Answer 1

Number of EXISTING CASES of a disease at a specific POINT IN TIME
(cross-sectional– only tested once, w/o follow up)

Question 2

Incidence

Answer 2

Number of NEW EVENTS (e.g., new cases of a disease) in a defined population within a SPECIFIC PERIOD

• -2 ways to measure
  1. Cumulative incidence
  2. incidence rate

Question 3

population at risk

Answer 3

individuals who have not had the disease but who are at risk of getting it
** denominator of incidence

Question 4

Risk

Answer 4

= incidence proportion = cumulative incidence

 This quantity has no units associated with it, but is always tied to a specified time interval
** numbers over time, can never go down

Question 5

incidence rate

Answer 5

= incidence density

 This quantity always has the unit of time in the denominator