1. Epidemiology Methods • Taken from the Toronto Notes • These MCQs do not all follow the current MCC guidelines (Oops ) Multiple Choice Questionsfor discussion

2. The purpose of randomization is to: a) make sure that there are equal numbers of men and women in test and control groups b) increase the chances of getting a statistically significant difference c) ensure that the numbers of cases and controls are equal d) limit bias e) all of the above

3. Which of the following types of studies usually provides only a measure of prevalence? a) descriptive b) cross-sectional c) randomized controlled trial d) cohort e) none of the above

4. A major advantage of cohort studies over case-control studies is that: a) they take less time and are less costly b) they can utilize a more representative population c) it is easier to obtain controls who are not exposed to the factor d) they permit estimation of risk of disease in those exposed to the factor e) they can be done on a “double-blind” basis

5. The incidence of a particular disease is greater in men than in women, but the prevalence shows no sex difference. The most probable explanation is that: a) the mortality rate is greater in women b) the case fatality rate is higher in women c) the duration of the disease is longer in women d) women receive less adequate medical care for the disease e) this diagnosis is more often missed in women

8. The following indicate the results of screening test “Q” in screening for disease “Z”: • The specificity of test “Q” would be: • a) 40/70 • b) 120/130 • c) 40/50 • d) 120/150 • e) 40/200

9. The positive predictive value would be: • a) 40/70 • b) 120/130 • c) 40/50 • d) 120/150 • e) 70/200

10. In which of the following study designs is the odds ratio the statistic typically used to show an association between cause and effect? a) a cross sectional/prevalence study b) a randomized controlled trial c) a cohort study d) a case study e) a case control study

11. Alpha error is: a) the probability of declaring a difference to be absent when it in fact is present b) the probability of declaring a difference to be present when it is not c) the probability of declaring a difference to be absent when it is indeed absent d) the probability of declaring a difference to be present when it does exist e) none of the above

12. Which one of the following descriptors of a diagnostic test is influenced by the prevalence of the disease being tested for: a) specificity b) sensitivity c) accuracy d) positive predictive value e) reliability

13. Each of the following statements applies to case control studies EXCEPT: a) starts with disease b) suitable for rare diseases c) relatively inexpensive d) prolonged follow-up required e) there may be a problem in selecting and matching controls

14. A clinician who has been examining the patterns of mortality in your community says that the rates for heart disease and lung cancer are higher in this community than in an adjacent community. Which of the following questions should you ask first? a) how did the clinician choose the comparison community? b) have the rates been standardized for age? c) are tobacco sales significantly different in the two communities? d) are the facilities to treat these diseases comparable in the two areas? e) are the numbers of deaths comparable in each area?

15. The effectiveness of a preventive measure is assessed in terms of: a) the effect in people to whom the measure is offered b) the effect in people who comply with the measure c) availability and the optimal use of resources d) the cost in dollars versus the benefits in improved health status e) all of the above

16. Of the five items listed below, the one which provides the strongest evidence for causality in an observed association between exposure and disease is: a) a large attributable risk b) a large relative risk c) a small p-value d) a positive result from a cohort study e) a case report

17. During a clinical trial, the difference in the success rates of two drugs was not statistically significant. This means that: a) there is no difference in drug effectiveness b) there is a sizeable probability that the demonstrated difference in the drugs’ effectiveness could occur due to chance alone c) the demonstrated difference in the drugs’ effectiveness is too small to be clinically meaningful d) the two samples of patients on which the drugs were tested came from the same population e) none of the above is true

18. All of the following statements about statistical tests are true EXCEPT: a) linear regression is used to describe the relationship between two continuous variables b) a confidence interval is a range of values giving information about the precision of an estimate c) ANOVA tables are used to make comparisons among the means of 3 or more groups simultaneously d) in a normal distribution, the mean, median and mode are equal e) the chi-square test evaluates the statistical significance of 2 or more percentages of categorical outcomes

19. More MCQs • Here are some more questions that students can use to test their own knowledge: http://www.medicine.uottawa.ca/sim/data/Self-test_Qs_Epi_Methods_e.htm • The questions contain comments on the answers, to illustrate why a given response is not correct