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Assignment I – Module 6 Case Study/ Problem Set – Measures of Association

Question 1: Several researchers felt that certain dietary habits increased an individual’s chance of developing colon cancer. To test this hypothesis, the researchers identified a group of patients whose initial diagnosis on admission was colon cancer. Another group of admitted patients with non-cancer diagnosis were used as a control group. Patients in both groups were interviewed to find out about their dietary habits. The interviewers did not know which patients had cancer and which did not. Table 1 shows data that resulted from the study.

1.    What type of study is this?

2.    On what basis dis you decide on the type of study it represents?

3.    Is there an association between exposure and the disease? Interpret your results. 

Question 2: To investigate the association between psychological variables and coronary heart disease, a group of researchers randomly sampled persons without coronary heart disease into groups as having behavior pattern type A and type B. These persons were followed over a period of time to see how many developed coronary heart diseases (CHD).

The type A behavior pattern is defined as manifesting an intense sustained drive for achievement and as being continually involved in competition and deadline. Type B is more relaxed, not showing this intense drive and involvement in competition. The researchers hypothesize that people with type A personalities will exhibit a greater amount of CHD because of the psychological stress of their way of life.  Table 2 shows data that resulted from the study.

1.    What type of study is this?

2.    On what basis dis you decide on the type of study it represents?

3.    Is there an association between exposure and the disease? Interpret your results. 

Question 3: In an earlier study of coronary heart disease and personality type, trained investigators were sent out to interview a random sample of people aged 40-59 in a small community. Each respondent was asked questions which established their personality as type A or type B. A medical history was taken to determine the presence or absence of coronary heart disease. Table 3 shows data that resulted from the study.

1.    What type of study is this?

2.    On what basis dis you decide on the type of study it represents?

3.    Is there an association between exposure and the disease? Interpret your results. 

Question 4: You are concerned about the relation between toxic waste sites and nervous system disorders. You identify 300 people who were recently diagnosed with nervous system disorders in Pennsylvania. This group includes all individuals diagnosed nervous system disorders in 2018. You then randomly select a group of 300 healthy individuals from Pennsylvania, frequency-matching on age, sex and county of residence. You find that those with nervous system disorders, 210 have a large toxic waste site within a mile of their home. Of the controls, 170 have a large toxic waste site within a mile of their home.

1.    What study design is this?

2.    On what basis did you determine the study design?

3.    Given the data above, create a 2X2 table.

4.    Calculate the appropriate measure of association between toxic waste site and nervous system disorders. Interpret your results.