Community Medicine Practice

20 learning units • 10 questions per unit • 200 explained questions

Module 02 — Epidemiological Measures & Comparisons

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Question 01 • Single best answer

Twenty new cases occur among 1,000 initially disease-free people with complete one-year follow-up. What is cumulative incidence?

A. 2% over one year B. 20% over one year C. 0.2% over one year D. 20 cases per person-year

Question 02 • Single best answer

Ten new cases occur during 500 person-years at risk. What is the incidence rate?

A. 2 per 1,000 person-years B. 50% prevalence C. 500 per 1,000 person-years D. 20 per 1,000 person-years

Question 03 • Single best answer

Longer survival with an incurable disease can cause which change when incidence is stable?

A. Increased prevalence B. Necessarily zero prevalence C. Necessarily doubled incidence D. Elimination of all existing cases

Question 04 • Single best answer

Five of 100 defined cases die during adequate follow-up. Which measure is 5%?

A. Case fatality proportion B. Population birth rate C. Incidence density D. Standardized mortality ratio

Question 05 • Single best answer

Risks of 20% and 10% yield which risk ratio?

A. 0.1 B. 10 C. 20 D. 2

Question 06 • Single best answer

Risks of 20% and 10% yield which risk difference?

A. 2 percentage points B. 50 percentage points C. 10 percentage points D. 200 percentage points

Question 07 • Single best answer

A one-year intervention reduces risk from 10% to 6%. What is its number needed to treat?

A. 4 for one year B. 40 for one year C. 25 for one year D. 250 for one year

Question 08 • Single best answer

Why might two populations need age standardization before mortality comparison?

A. All deaths have identical causes B. Standardization eliminates every bias C. Their populations must be exactly equal D. Their age distributions differ

Question 09 • Single best answer

Which denominator defines incidence density?

A. All existing cases only B. Number of hospital beds C. Number of deaths only D. Person-time at risk

Question 10 • Single best answer

Which statement about an odds ratio is safest?

A. It need not equal the risk ratio B. It always equals absolute risk reduction C. It always measures prevalence directly D. It is always between zero and one