This lecture was given as a part of the Introduction to Epidemiology & Community Medicine Course given for third-year medical students.

10. Source: https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson3/section2.html
In 2003, 44,232 new cases of acquired
immunodeficiency syndrome (AIDS) were reported
in the United States. The estimated mid-year
population of the U.S. in 2003 was approximately
290,809,777. Calculate the incidence rate of AIDS
in 2003.
Numerator = 44,232 new cases of AIDS
Denominator = 290,809,777 estimated mid-year
population
10n = 100,000
Incidence rate = (44,232 ⁄ 290,809,777) × 100,000
= 15.21 new cases of AIDS per 100,000 population
Example Calculating Incidence Rates

12. Source: https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson3/section2.html
In a survey of 1,150 women who gave birth in
Maine in 2000, a total of 468 reported taking a
multivitamin at least 4 times a week during the
month before becoming pregnant.
Calculate the prevalence of frequent multivitamin
use in this group.
Numerator = 468 multivitamin users
Denominator = 1,150 women
Prevalence = (468 ⁄ 1,150) × 100 = 0.407 × 100 =
40.7%
Example Calculating Prevalence