Question 1
1. The following table describes hypothetical age-specific rates of heart disease in India and the United States in 2009. Also included are hypothetical age distributions for the two countries and the entire world population.
Age Group
(in years) % of Population in Age Group Heart Disease Rate per 100,000 person-years
INDIA U.S.A. WORLD INDIA U.S.A.
< 30 60% 30% 50% 50 75
30-55 30% 40% 30% 80 150
> 55 10% 30% 20% 120 400
o Calculate the crude rate of heart disease for each of the two countries. Suppose that you want to compare the rate of heart disease in India to that in the United States. You know that age is an important risk factor for heart disease. Examine the age distribution of each country’s population.
o Should you use the two crude rates to compare the two countries? Why or why not?
o Calculate an age-adjusted rate for heart disease in each country. Use the age distribution of the entire world as your standard.
o Based on these answers, would you say that the age differences between India and the United States account for the entire difference in crude heart disease rates between the two countries? Why or why not?
Question 2

Phthalates are present in many diverse products, including insect repellents, body lotions, perfumes, and food packaging. Because animal experiments suggest that phthalates may have an adverse effect on the male reproductive system, a group of infertility specialists decided to conduct a case-control study on phthalate exposure and sperm abnormalities in adult men.100 cases with sperm abnormalities and 100 controls were identified and enrolled from among patients at their infertility clinic. 30 cases and 10 controls had high urinary phthalate levels; the remainder had normal urinary phthalate levels.
Set up and fill in the two by two table using these data
Use these data to calculate the odds ratio describing the relationship between phthalate levels and sperm abnormalities
State in words your interpretation of this odds ratio
Question 3
1. For this problem, note the following chart:
Age Group
(in years) % of Population in Age Group Influenza Rate per 1,000 person-years
CITY A CITY B CITY C Massachusetts CITY A CITY B CITY C
YOUNG 40% 50% 80% 60% 2 10 30
OLD 60% 50% 20% 40% 70 110 5
2.
3. There are 10,000 individuals in City A, which is located in Massachusetts. Eight young individuals and 420 old individuals develop the flu over the course of a year.
o Use these data to calculate the crude influenza rate per 1,000 individuals per years in City A.
o What is the crude rate of influenza in City B?
o What is the crude rate of influenza in City C?
o Calculate an age-adjusted influenza rate for each of the cities. Use the age distribution for the State of Massachusetts (shown in the table) as the standard.