QUESTION 1

In large samples, the sampling distribution of the risk difference is approximately ?â€¨

a-normal

b-

Skewed

c. t

d. F

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0.67 points

QUESTION 2

Plus-four confidence interval method for a difference in proportions is accurate in samples as small as â€¨

a. 100 per group

b. 50 per group

c. 25 per group

d. 5 per group

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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?â€¨

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.

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QUESTION 4

Which of the following is not an example of systematic error in an observational study?â€¨

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 Alzheimerâ€™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.

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0.67 points

QUESTION 5

Proportions are tested for a significant _____ difference?â€¨

a. â€œrandomâ€

b. â€œnonrandomâ€

c. â€œindifferentâ€

d. â€œnoisyâ€

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QUESTION 6

What is not a method for testing proportions for significance?â€¨

a. z test (large sample)

b. Fisherâ€™s exact procedure (small samples)

c. the chi-square test

d. the Wassermann test

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QUESTION 7

In calculating for tests of proportions for small samples (fewer than 5 successes expected in either group), avoid the z test and useâ€¨

a. the exact Fisher or Mid-P procedure

b. the asymptotic procedure

c. the random event generator

d. the special theory of relativity

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QUESTION 8

Before conducting Fisherâ€™s test, data are rearranged to form a â€¨

a. 1-by-2 table

b. 2-by-1 table

c. 2-by-2 table

d. A single row table

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QUESTION 9

The best way to calculate a p value for a Fisherâ€™s Exact is toâ€¨

a. Use an adding machine

b. Use computer program

c. Call a statistician

d. Use pencil and paper

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QUESTION 10

The RR (risk ratio or prevalence ratios) is a risk â€¨

a. multiplier, e.g., an RR of 2 suggests that the exposure doubles risk

b. adder, e.g., an RR of 2 suggests that the exposure sums risk

c. divider, e.g., an RR of 2 suggests that the exposure divides risk

d. neutralizer, e.g., an RR of 2 suggests that the exposure neutralizes risk

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0.67 points

QUESTION 11

When p1 = p2 , RR = 1. â€¨

a. This is the â€œmultiplier RR,â€ indicating increased association.

b. This is the â€œbaseline RR,â€ indicating no association.

c. This is the â€œsmall effect RR,â€ indicating slightly increased association.

d. This is the â€œpopulation RR,â€ indicating population prevalent association.

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QUESTION 12

An RR of 1.15 indicates â€¨

a. No association;

b. a negative association; specifically, 15% lower risk (in relative terms) with exposure.

c. a positive association; specifically, 15% higher risk (in relative terms) with exposure.

d. a positive association; specifically, 115% higher risk (in relative terms) with exposure.

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0.67 points

QUESTION 13

In observational studies, systematic errors are often _____important than random sampling error?â€¨

a. Less

b. Equally

c. More

d. None of the above

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QUESTION 14

The three types of systematic error considered do not includeâ€¨

a. Confounding

b. Information bias

c. Selection bias

d. Random sampling error

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QUESTION 15

Nondifferential misclassification tends to bias results â€¨

a. Away from the null and show a positive effect.

b. can bias results in either direction.

c. toward the null (or have no effect).

d. Away from the null and show a negative effect.

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0.67 points