A cohort study was conducted to study the association of coffee drinking and weight gain in a population-based sample of adults. Among 14,000 coffee drinkers, 700 experienced weight gain after two years of follow up. Among the 18,000 non-coffeedrinkers, 360 experienced weight gain in the same study 2-year period. What is the relative risk for the association of coffee drinking (yes vs. no) with weight gain (yes vs. no) (assume complete follow up for all participants)?

	A.	2.65
	B.	2.85
	C.	2.5
	D.	2.25
	E.	2.5 per 1000 person years
	F.	0.4

A large medical centers oncology program reported an increased number of cases of pancreatic cancer during a certain month. The hospitals epidemiologist decided to research the problem. Tumor registry records were searched to identify all cases of pancreatic cancer during a five-year period; pancreatic cancer patients were matched with patients treated for other diseases during the same five-year period. All subjects in the study were questioned about lifestyle factors including alcohol, tea, and coffee consumption. The resulting data are as follows:

DATA
	Pancreatic Cancer Patients	Other Control Patients
	Men	Women	Men	Women
LIFESTYLE VARIABLE
Alcohol	180	120	250	260
Tea Drinking	140	110	230	225
Coffee Drinking	190	140	270	240

Note:

Total number of male pancreatic cancer patients = 200. Total number of female pancreatic cancer patients = 150. Total number of male patients (other diseases) = 300. Total number of female patients (other diseases) = 300.

Which number best estimates the association of no alcohol drinking with pancreatic cancer in men?

	A.	1.9
	B.	2.1
	C.	0.56
	D.	1.8

The members of a public health team are engaged in planning where to open a specialty diabetes clinic to provide care for patients with the disease in a large city. Which of the following designs would you recommend?

	A.	A case-control studywith a random sample of the city's residents.
	B.	A cross-sectional surveyof a random sample of patients with diabetes
	C.	A retrospective cohort study with a random sample of the city's residents
	D.	An ecologic study with a random sample of the city's residents
	E.	A cross-sectional studywith a random sample of the city's residents

The table below shows results form a randomized clinical trial that was conducted to evaluate the effectiveness of treating HIV-positive women with zidovudine during pregnancy in reducing maternal-infant HIV transmission.

Maternal-Infant transmission of HIV with Zidovudine Treatment (Results from a randomized clinical trial)

	Infant HIV Infection
Treatment	Yes	No	Total
Yes (Zidovudine)	13	167	180
No (placebo)	40	143	183

Based on these results, the number needed to treat to prevent one mother-infant transmission of HIV is:

	A.	8
	B.	7
	C.	6
	D.	4