HOME WORK QUESTION 1 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 2 Recently, a report was published describing a string of cases of Norwalk virus gastroenteritis among passengers on cruise ships. From this report, an epidemiologist went on to form a number of hypotheses as to why there had been this rather unusual increase in reported gastroenteritis outbreaks on cruise ships in 2012. The cruise ship owners contacted the Centers of Disease control and Prevention (CDC) to conduct an indepth analysis of the possible modes of transmission of the Norwalk virus in the cruise ship environment. CDC investigators interviewed all of the passengers on the last affected cruise (N=3,000) and obtained information on the passenger's recreational activities. They found the following results: 1,000 passengers had gone swimming in the upper deck pool and 2,000 passengers had never gone swimming in the upper deck pool. 100 of the passengers who swam in the upper deck pool and 100 of the passengers who did not swim in this pool developed Norwalk virus gastroenteritis during the cruise. FYI: The cruise lasted one week. Set up the 2x2 table for these data. Calculate the risk ratio of gastroenteritis associated with swimming in the upper deck pool. State in words your interpretation of the above risk ratio Calculate the risk difference in the above example State in words your interpretation of the above risk difference 1. QUESTION 3 For this problem, note the following chart: Age Group % of Population in Age Group Influenza Rate per 1,000 (in years) person-years CITY A CITY B CITY C Massachuset CITY A CITY B CITY ts 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. 4.Question Over 25 studies have been conducted which have failed to show an association between MMR vaccine and autism. Below is a data from ( case-control). Calculate the measure of association for each study after completing the 2x2 table and interpret the measure of association. Case control study by Smeeth et al (Lancet 2004) 1294 cases of pervasive developmental disorder (PDD) and 4469 controls were included. 1010 cases (781%) had MMR vaccination recorded before diagnosis, compared with 3671 controls (821%) before the age at which their matched case was diagnosed