Question

1. The data of a major referral hospital showed that most patients with ischemic heart disease (IHD) were black American. Based on this, it was concluded that black Americans are at higher risk of IHD compared to other community groups.

   How would you describe the conclusion?

   	A.	Correct, because risk factors for IHD are more common in black African American.
   	B.	Incorrect, because no test of statistical significance has been made
   	C.	Incorrect, because prevalence is used instead of incidence
   	D.	Incorrect, because there is no appropriate denominator in this comparison
   	E.	Incorrect, because the sample was too small.

0.5 points   

QUESTION 2

1. What type of error we commit when we conclude that there is a difference while in reality there is not?

   	A.	Type II error
   	B.	Standard error
   	C.	Power error
   	D.	Type I error
   	E.	ß error

0.5 points   

QUESTION 3

1. For each component of basic reproductive number, select the most appropriate intervention from the following lettered options. Assume the disease spreads via droplets.

   -       A.       B.       C.    Probability of infection given the exposure       -       A.       B.       C.    Duration of infectious period       -       A.       B.       C.    Number of contacts per time unit

   A. Wearing face mask   B. Early detection and early treatment C. Isolation

1 points   

QUESTION 4

1. In small town with a large university campus, there was a report indicating a significant increase in the number of cases of food poisoning at the beginning of the academic year. The only hospital serving the city has reported a 25% increase in the cases of food poisoning.

   What is the most likely explanation?

   	A.	Sudden change in the population
   	B.	Change in eating habits and food preparation
   	C.	Diagnostic mistakes due to new diagnostic technique.
   	D.	Food poisoning caused by a new organism
   	E.	Seasonal variation in food poisoning

0.5 points   

QUESTION 5

1. Which of the following will help you to demonstrate that Type 2 diabetes is a major health problem in the US?

   	A.	Risk ratio for type 2 diabetes
   	B.	Relative risk for diabetes
   	C.	Odds ratio for type 2 diabetes
   	D.	Case fatality for type 2 diabetes
   	E.	Prevalence of type 2 diabetes

0.5 points   

QUESTION 6

1. A cross-sectional study aimed to measure the prevalence of asthma among cement factory workers. Theresearcher included 1000 men who are currently working in cement factories. The researcher found that the prevalence of asthma in cement factory workers is much lower than that reported in general population.

   What may explain his/her conclusion?

   	A.	Small sample size affected the results
   	B.	Wrong data analysis
   	C.	Workers are being protected from cement dust
   	D.	Respiratory health is not affected by cement dust
   	E.	Healthy worker effect

0.5 points   

QUESTION 7

1. Clinicians see only a few cases in their clinics while, many cases remain undiagnosed in the community. What is this called?

   	A.	Isolation
   	B.	Iceberg concept of disease
   	C.	Quarantine
   	D.	Epidemic
   	E.	Endemic

0.5 points   

QUESTION 8

1. A review of 7 cohort studies has shown that coronary heart disease risk is the highest among individuals with sedentary life style compared to physically active individuals after considering the gender (relative risk = 4.1; 95 CI: 1.9-5.8).

   From these findings which of the following Bradford Hills’ criteria can be judged?

   	A.	Specificity, coherence, temporality
   	B.	Biological plausibility, alternate considerations, consistency
   	C.	Consistency, coherence, strength of association
   	D.	Strength of association, specificity, alternate considerations
   	E.	Temporality, consistency, strength of association

QUESTION 9

1. A randomized controlled trial assessed the effect of aggressive versus usual blood pressure control among hypertensive diabetics. They report the following in the methods section: “Analysis was on an intention-to-treat basis, comparing patients allocated to aggressive and usual blood pressure control."

   What is the purpose of the analytical procedure they described?

   	A.	Keep the random allocation of patients intact
   	B.	Adjust for confounding effects
   	C.	Ensure an analysis regarding what participants actually received
   	D.	Minimize losses to follow-up
   	E.	Avoid information bias

QUESTION 10

1. The table below shows the results of a cohort study that aimed to estimate the risk of mortality due to respiratory diseases among oil refinery workers. The cohort comprised 10,000 men who had worked in oil refineries between 2010 and 2015. During this period 300 deaths occurred among this cohort. These were compared to the expected number of death as derived from mortality rates for population.

   Cause of death	Observed death in oil refineries	Expected death in the population
   Respiratory diseases	300	500

   a) Calculate the appropriate measure of association

   b) What is your conclusion? (0.5 point)

   c) Provide an explanation for the findings above.

QUESTION 11

1. In a trial of a vaccine against measles, 1500 randomly selected children were given the vaccine and followed for ten years. Of these, 95% never developed measles.

   What does this suggest about the efficacy of the vaccine?

   	A.	No conclusion about efficacy is possible, since there is no comparison with non-vaccinated children.
   	B.	The vaccine has high efficacy, since it kept 95% of the vaccinated children from developing the illness.
   	C.	The vaccine has high efficacy because of the high rate of immunization.
   	D.	The p-value for the efficacy is 0.05, equal to the cumulative incidence of the illness.
   	E.	The vaccine has low efficacy because it should have produced a higher immunization rate.

0.5 points   

QUESTION 12

1. Communities X and Z have equal age-adjusted mortality rates. Community X has a lower crude mortality rate than Z.

   What is the main conclusion?

   	A.	Both communities have identical age distribution.
   	B.	Diagnosis is more accurate in X than Z.
   	C.	Diagnosis is less accurate in X than Z.
   	D.	X has an older population than Z.
   	E.	X has a younger population than Z.

Answer 1

1) a -Coreect ,because risk factors for IHD are more common in black African American.

2) e - beta error - statistical error when conclude that something is negative when it is really positive.

3) Probability of infection given the exposure - early detection and early treatment

Duration of infectious period - isolation

Number of contacts per time unit - wearing face mask

4) c - food poisoning caused by a new organism

5) e - prevalence of type 2 diabetes

6) a - small.sample size affected the result

7) b - iceberg concept of disease