## Problem Set: Measures of Association and Impact

After gaining information and advice from your peers in the Discussion, this Assignment will allow you to practice individually and increase your skills with measures of association and impact. Your goal for this Assignment is to compute and interpret measures of association and impact.

To prepare for this Assignment, you must have mastered the materials, clarify any questions you may have about the material presented in the textbook, demonstration video, or any chapter questions at the ends of the assigned chapters.

Assignment Details

 There are 3 questions that have been assigned to you for your problem set.
 You are expected to complete all problems, showing your work.
 Be sure that your completed problem set includes your responses to all questions and shows the calculations and/or reasoning to justify all answers.

QUESTION 1
Recently, Australian researchers conducted a study of the relationship between optimism and colon cancer survival. Their hypothesis was that colon cancer patients who had a positive outlook on life would have a lower five-year cumulative incidence of mortality. The study included 100 recently diagnosed colon cancer patients who underwent psychological testing and were found to have a optimistic outlook on life and 100 recently diagnosed colon cancer patients who underwent the same psychological tests and were found to have a pessimistic outlook on life. By the end of five years of follow-up, 50 of the 100 patients with the optimistic outlook and 75 of the 100 patients with the pessimistic outlook had died from colon cancer.
• Set up and fill in the two by two table using these data.
• What is the prevalence of colon cancer in the study population?
• Compare the cumulative incidence of mortality in the optimistic group to the cumulative incidence of mortality in the pessimistic group using a ratio measure of association.
• State in words your interpretation of the result you found in part c.

QUESTION 2
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

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.
• Use these data to calculate the crude influenza rate per 1,000 individuals per years in City A.
• What is the crude rate of influenza in City B?
• What is the crude rate of influenza in City C?
• 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.

QUESTION 3
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