PH 384: Introduction of Epidemiology:
Assignment 2 (100 points possible)
1. Here is an example of case-control study. You want to do a study to see if
SUCRALOSE (artificial sugar) is a risk factor for pancreatic cancer. You
assemble a sample of 1000 pancreatic cancer cases from a cancer registry
and 1000 controls (people without the disease) using random digit dialing. Of
the cases, 500 did not use SUCRALOSE; Of the controls, 800 did not use
1) Construct contingency table.
2) Answer the following questions:
Of people who had SUCRALOSE, what is percentage of them had
Of people who do not take SUCRALOSE, what is percentage of them
had pancreatic cancer?
3) Calculate odds ratio
4) Interpret odds ratio
2. In 2005, an investigator drew a random 1000 sample of all adults without a
chronic disease in a community. At this time point, forty (40%) percent of
people without the disease had a particular exposure, which is fixed. Within
the next five years, 55 cases of the disease occurred in the study population,
and 40 of these cases were exposed. Assume steady state conditions and
that the exposure is not a prognostic factor for the disease.
5) Construct contingency table.
6) Estimate relative risk of exposure
7) Interpret relative risk of exposure
8) Estimate the attributable risk to exposure
9) Estimate the population risk difference
3. WKU is trying to determine whether to screen students for disease x, which is
highly communicable and preventable. Preliminary data from a pilot test
showed the following results: Of the 1000 people who actually had disease x,
680 tested positive. Of the 3000 people without the disease, 400 tested
a. Complete a 2×2, then answer the following questions
b. What is the sensitivity of the screening test ?
c. What is the specificity of the screening test?
d. What is the PPV of the screening test?
e. What is the NPV of the screening test ?
f. Prove a summary for the screening test or do you consider this screening
test a good screening test? (Refer the summary in the slide 48 on lecture
notes from chapter 8&9)
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