QUESTION 1 In large samples, the sampling distribution of the risk difference is approximately ? a-normal b- Skewed c. t d. F 0.67 points QUESTION 2 Plus-four confidence interval method for a difference in proportions is accurate in samples as small as a. 100 per group b. 50 per group c. 25 per group d. 5 per group 0.67 points QUESTION 3 Which of the following is not a requirement for consideration before continuing with the calculation of a sample size in an observational study observing the difference in incidence of disease X based on exposure? a. Projected drop-out rate to inflate the sample size estimate based on the projected loss to follow-up in a study. b. A predetermined power for the study to detect a difference when one actually exists. c. The correlation coefficient between the two groups being compared. d. The informed estimation of the incidence in both groups being compared. 0.67 points QUESTION 4 Which of the following is not an example of systematic error in an observational study? a. A cross-sectional study recruits participants that are willing to sign up outside of a major university and meet the inclusion and exclusion criteria to take part in the survey relating unsafe sex habits to STIs. b. A researcher is interested in the relationship between coffee drinking and lung cancer, and after careful multivariate linear regression modeling determines that a significant percentage of the relationship is due to another variable, cigarette smoking. c. An observational study recruits participants for a study looking at Alzheimer’s disease due to exposure to industrial hazards by asking participants to recall their exposure over the past 10 years. d. A data-entry specialist responsible for adding in fasting glucose levels to a database accidentally skipped an observation during the input phase of data cleaning. 0.67 points QUESTION 5 Proportions are tested for a significant _____ difference? a. “random” b. “nonrandom” c. “indifferent” d. “noisy” 0.67 points QUESTION 6 What is not a method for testing proportions for significance? a. z test (large sample) b. Fisher’s exact procedure (small samples) c. the chi-square test d. the Wassermann test 0.67 points QUESTION 7 In calculating for tests of proportions for small samples (fewer than 5 successes expected in either group), avoid the z test and use a. the exact Fisher or Mid-P procedure b. the asymptotic procedure c. the random event generator d. the special theory of relativity 0.67 points QUESTION 8 Before conducting Fisher’s test, data are rearranged to form a a. 1-by-2 table b. 2-by-1 table c. 2-by-2 table d. A single row table 0.67 points QUESTION 9 The best way to calculate a p value for a Fisher’s Exact is to a. Use an adding machine b. Use computer program c. Call a statistician d. Use pencil and paper 0.67 poi.