Nokea
A random-digit dialed survey conducted in the City of Long Beach, California, reported that a greater proportion of nonsmokers endorsed a ban on smoking in alcohol-serving establishments than did smokers. What type of study design was this?
- A. Cross-sectional study
- B. Case-control study
- C. Ecologic study
- D. Cohort study
Correct Answer: A
Rationale: This is a cross-sectional study as it captures attitudes at one point in time without follow-up.
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A local health department epidemiologist investigated an outbreak of gastrointestinal illness thought to be associated with a college cafeteria. There were many complaints about the quality of the cafeteria's offerings, and it appeared that the students' worst expectations were confirmed when several students visited the college's infirmary during the middle of the night and the following day complaining of nausea, diarrhea, fever, vomiting, and cramps. The health department's investigation revealed that 24 students had eaten in the cafeteria immediately before the outbreak. The times between eating in the cafeteria and the development of active symptoms ranged from 20 to 36 hours. A list of foods eaten, the number of persons eating the foods, and tabulations of illness are presented in Appendix 12. Fill in the attack rates where indicated. On the basis of your calculations, answer the following questions: What food or foods would you suspect caused the problem?
- A. Chicken salad
- B. Potato salad
- C. Both A and B
- D. Neither A nor B
Correct Answer: C
Rationale: High attack rates for both chicken and potato salads suggest they were contaminated.
Two automated blood cell counters are tested twice using a prepared suspension of leukocytes containing 8,000 cells/mm3. The cell counts by device A are 8,400 cells/mm3 the first time and 8,350 cells/mm3 the second. Device B's counts are 8,200 and 7,850 cells/mm3, respectively. Which device(A or B) gives leukocyte counts with greater validity?
- A. Device A
- B. Device B
- C. Both devices have equal validity
- D. Neither device is valid
Correct Answer: A
Rationale: Validity refers to how close the measurements are to the true value (8,000 cells/mm3). Device A's measurements (8,400 and 8,350) are closer to the true value than Device B's (8,200 and 7,850).
The common characteristic that both experimental and quasi-experimental study should possess is
- A. Manipulation
- B. Control groups
- C. Randomization
- D. None
Correct Answer: A
Rationale: Both experimental and quasi-experimental studies involve manipulation of variables.
Identify the type of study design described: The physical examination records of the incoming first-year class of 1935 at the University of Minnesota are examined in 1980 to see whether the freshmen's recorded height and weight at the time of admission to the university were related to their chance of developing coronary heart disease by 1981.
- A. Cohort study
- B. Case-control study
- C. Cross-sectional study
- D. Ecological study
Correct Answer: A
Rationale: This retrospective analysis constitutes a cohort study linking baseline characteristics to future outcomes.
How would the clinical and epidemiologic descriptions of a disease differ, and how would they be similar?
- A. Clinical focuses on individual cases; epidemiologic focuses on populations.
- B. Clinical uses laboratory tests; epidemiologic uses surveys.
- C. Clinical focuses on treatment; epidemiologic focuses on prevention.
- D. Both focus on identifying disease causes.
Correct Answer: A
Rationale: Clinical descriptions emphasize individual diagnosis and treatment, while epidemiologic descriptions analyze patterns and causes in populations.