In a certain noisy factory, workers are provided with earplugs and are expected to wear them. An industrial hygienist inspecting the plant found that 100 of the 500 workers in the factory were not wearing their earplugs because they regarded them as uncomfortable and a nuisance. When all the workers were given a hearing test, it was found that 4 of the earplug wearers and 10 of the non-wearers had developed significant hearing loss. All had had normal hearing at their pre-employment examinations one year earlier, when the plant opened.

QUESTION 1

1. What was the cumulative incidence rate of hearing loss in workers who did not wear earplugs?

1 points

QUESTION 2

1. What was the relative risk of hearing loss in workers who did not wear earplugs, compared with those who did?

1 points

QUESTION 3

1. What was the risk of hearing loss attributable to not wearing earplugs? (i.e., what was the risk difference?)

1 points

QUESTION 4

1. What proportion of hearing loss in the nonwearers was attributable to not wearing earplugs?

1 points

QUESTION 5

1. What proportion of the hearing loss in all the workers was attributable to not wearing earplugs?

1 points

QUESTION 6

1. A psychologist has developed a test for school children that is supposed to identify who will commit violent crimes during adolescence and young adulthood. In one school 10 percent of the 200 children tested show a positive result, indicating criminal potential. Half of these children do indeed go on to commit violent crimes, whereas only 5 percent of those who tested negative do so. These data are entered into the table below:

   	Violent	Not Violent	Total
   Test Positive	10		20
   Test Negative	9		180
   Total	19		200

   What is the observed agreement between the test and the result?

1 points

QUESTION 7

1. What is the expected agreement between the test and the result in the previous question?

1 points

QUESTION 8

1. Calculate the kappa statistic for the scenario in #6.

1 points

QUESTION 9

1. For which of the following study questions would a case-crossover study design be appropriate?

   Is the lifetime risk of lymphoma elevated in x-ray technicians?

   Is there an increased risk of asthma attacks during the hour following intense exercise?

   Do people with sickle-cell trait have lower risk of malaria than people without it?

   Do data entry clerks have an elevated risk of carpal tunnel syndrome?

1 points

QUESTION 10

1. Type II error happens when a researcher:

   Rejects a true null hypothesis

   Fails to reject a false null hypothesis

   Rejects a false null hypothesis

   Fails to reject a true null hypothesis

1 points

QUESTION 11

1. A screening test for a certain disease detects it on average two years earlier than was previously possible. A study shows that after this test was introduced, the average survival time for patients who had the disease detected by the new test was two years longer than patients who did not have the test. This is an example of:

   Increased survival

   Decreased induction time

   Lower case fatality rate

   Lead time bias

1 points

QUESTION 12

1. List two ways by which you might control for confounding

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2 points

QUESTION 13

1. List two examples of information bias

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2 points

QUESTION 14

1. List two examples of selection bias.

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2 points

QUESTION 15

1. As the prevalence of a disease increases, the positive predictive value of a screening test will:

   Increase

   Decrease

   Not be affected

   All of the above

1 points

QUESTION 16

1. What are the three elements of the epidemiologic triad?

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1 points

QUESTION 17

1. The interval from infection to the onset of clinical illness is known as the:

   Incubation period

   Lead time

   Secondary period

   Latent period

1 points

QUESTION 18

1. How would you determine whether a 95% confidence interval of an odds ratio is statistically significant?

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1 points

QUESTION 19

1. Using the standard population distribution given in the table below, use the direct method to calculate the age-adjusted rates (per 100,000) for each of the racial groups. Perform your calculations to two decimal places.First, calculate the age adjusted rate for the White racial group.

   Age in Years	Standard Population	Age Specific Rates (per 100,000)
   White	Black	API
   <50	12562269	49.13	40.00	36.92
   50-54	1359483	245.61	220.38	171.04
   55-59	1135038	313.56	271.39	200.62
   60-64	810656	380.19	323.89	217.09
   65-69	621866	428.23	345.39	194.85
   70+	2012845	443.60	384.31	209.49
   Total	18502157

1 points

QUESTION 20

1. From the previous table, calculate the age adjusted rate for the Black racial group.

1 points

QUESTION 21

1. Calculate the age adjusted rate for the API racial group.

1 points

QUESTION 22

1. 100 adults were enrolled in a study on aging. At the baseline examination, 14 were found to have arthritis. In a follow-up examination one year later, six stated that they had been diagnosed with arthritis since the baseline examinationWhat was the point prevalence of arthritis at baseline?

1 points

QUESTION 23

1. What was the one-year period prevalence of arthritis in the previous example?

1 points

QUESTION 24

1. What was the cumulative incidence of arthritis during the study period?

1 points

QUESTION 25

1. In a certain city with a population of 1 million people, 5,000 people died last year. In the same city 10,000 were known to have cancer last year, of whom 500 died. What was the total annual mortality rate per 100,000 in the city last year?

1 points

QUESTION 26

1. What was the proportionate mortality from cancer in the previous scenario?

1 points

QUESTION 27

1. What was the case fatality rate from cancer?

1 points

QUESTION 28

1. A prominent oncologist decides to conduct a randomized trial, in which his patients are randomized to either the current therapy or a new treatment. If the mortality rate on the current therapy is 8% and the mortality rate for patients on the new treatment is 4%, how many patients would he need to treat to prevent one death?

1 points

QUESTION 29

1. Two radiologists review the same set of x-rays for signs of lung cancer. If radiologist A codes 25 as positive and 75 as negative, and radiologist B codes 32 as positive and 68 as negative, how many x-rays would we expect to be coded POSITIVE by both radiologist AandB?

1 points

QUESTION 30

1. A matched pairs case-control study of asthma and exposure to pet birds is conducted, with the following findings: In 5 pairs, both the case and control were exposed to pet birdsIn 10 pairs, the case was exposed to a pet bird, but the control was notIn 4 pairs, the control was exposed to a pet bird, but the case was notIn 21 pairs, neither the case nor the control was exposed to a pet birdWhat is the matched-pairs odds ratio for exposure to pet birds?

1 points

QUESTION 31

1. The results of a twin study would be suggest that a disease is genetically determined if:

   Monozygotic twins have a higher degree of concordance

   Dizygotic twins have a higher degree of concordance

   Monozygotic twins have a higher degree of discordance

   Dizygotic twins have a higher degree of discordance

1 points

QUESTION 32

1. Nondifferential misclassification (where cases and controls are equally likely to forget details about their exposure histories) tends to produce estimates of effect that are:

   Underestimated (closer to the null value than they should be)

   Exaggerated (further from the null value than they should be)

   Sometimes exaggerated, sometimes underestimated

   Highly variable

1 points

QUESTION 33

1. According to the article, "Red Meat Consumption and Mortality," a 1-serving per day increase in red meat consumption leads to an elevated risk of:

   Mortality

   Cardiovascular disease

   Cancer

   All of the above

1 points

QUESTION 34

1. People who take aspirin regularly have a lower risk of lung cancer than people who do not take aspirin TrueFalse