A screening test is used in similar way of 2 populations, but the population of false positive results in population A is increased than in population B. What is the reason?

A- Specificity of test is increased in Population A

B- Specificity of test is decreased in Population A

C- Prevalence of disease is increased in Population A

D- Prevalence of disease is decreased in Population A

2.OutcomeTotal

Factor+-

PositiveABA+B

NegativeCDC+D

TotalA+CB+DA+B+C+D

Assuming it is a cohort study, define the risk difference or attributable risk?

A. a/a+b/ b/b+dB. a/a+b / c/c+dC.a/a+c / b/b+dD. a/a+b / c/c+dE. None of the above.

3. The death rate per 100,000 for lung cancer is 71 among non- smokers, 422 of coronary thrombosis among non-smokers. The prevalence of smokers in the population is 55%. The relative risk of dying for a smoker compared to a non- smoker is?

A. 10.1 for lung cancer and 8.4 for coronary thrombosis.

B. 10.1 for lung cancer and 1.4 for coronary thrombosis.

C. 9.1 for lung cancer and 0.3 for coronary thrombosis.

D. 9.1 for lung cancer and 1.4 for coronary thrombosis.

E. 12.4 for lung cancer and 1.7 for coronary thrombosis.

4. If it accepted that an observed association is a causal one, an estimate of the impact that a successful preventive program might have can be derived from?

A. Higher life expectancy. B. Attributable Risk. C. Prevalence Rate.D. Relative RiskE. All of the above.

5. A Screening exam was performed on 250 patients for Factor X, which is found on disease Y. A definitive diagnosis for disease Y among 250 patients had been obtained previously, with the results below.

Result of Diagnosis.

Test ResultsDisease PresentDisease Absent

Positive for Factor X4060

Negative for Factor X10140.

The Sensitivity test is ?

A. 70%B. 56%C. 7%D. 30%E. 80%

6. A lyme disease screening test is developed for use in a population. The Sensitivity and Specificity of the new test are 60% and 70% respectively, 300 people are screened at the clinic 1st year the test is implemented. Assuming the true population of lyme disease among clinic attendees is 10%. Calculate the following? The Predictive value of a positive test is?

A. 94.0%B. 22.2%C. 33.0%D. 18.2%E. 6.0%

7. Also calculate the number of false positive? from question number 6.

A. 99%B. 81%C. 9%D. 12%E. 2,162

8. Choose the best answer. A test developed to access Age- related changes in Bone density that does not pick up these changes has?

A. Low concurrent validity.B. None of the options listedC. Low predictive valueD. Low construct validity.

9.A. Reliable- InvalidB. Unreliable- InvalidC. Reliable- Valid

From the different combinations of Validity and Reliability, Which option represent High Validity?

A2. B3. Both A and C4. None of the above.

10. Specificity refers to the ability of a screening test to identify non-diseased individuals who actually do not have the disease.

A. TrueB. False.

11. The purpose of a double-blind study in clinical trial is

A. Decrease error from the way outcome is accessed.

B. Decrease error from subjects knowledge of their assignment to study conditions

C. Decrease error from non-random assignment to study condition

D. A and B only

E. All of the above.