Research & Evidence-Based Medicine

20 learning units • 100 chapter sections • 200 explained questions. Build a question, judge the evidence and connect the answer with the person receiving care.

Original RAHBAR study material for the Year 3 learning pathway. Educational examples support supervised learning; institutional research and clinical requirements still apply. References & further reading ↓

MODULE 09 / 20

Risk, Odds & Absolute Treatment Effects

Translate comparative results into understandable numbers with a stated population and time horizon.

Answer all 10 questions, then submit to see your score and explanations. This is a self-study exercise; results are not saved.

Question 01. Events occur in 10/100 intervention and 20/100 control patients. What is the risk ratio? A. 2B. 0.1C. 0.5D. 10

Question 02. For risks of 20% versus 10%, what is the absolute risk reduction? A. 50 percentage pointsB. 2 percentage pointsC. 100 percentage pointsD. 10 percentage points

Question 03. What NNT corresponds to an absolute risk reduction of 0.10? A. 10B. 0.1C. 100D. 1

Question 04. What is the relative risk reduction when RR is 0.5 for an adverse outcome? A. 5%B. 0.5%C. 50%D. 150%

Question 05. What are the odds for a probability of 20%? A. 0.25B. 0.20C. 0.80D. 4

Question 06. Which value is the null for a risk ratio? A. 0B. 100C. -1D. 1

Question 07. What denominator defines an incidence rate? A. Person-time at riskB. Only prevalent casesC. The number of study authorsD. Only positive test results

Question 08. At baseline risk 2%, an assumed RR of 0.5 gives what absolute reduction? A. 50 percentage pointsB. 1 percentage pointC. 10 percentage pointsD. 2 percentage points

Question 09. Why must an NNT include a time horizon? A. Event accumulation and absolute benefit depend on follow-upB. NNT is always timelessC. It replaces the comparatorD. It proves the effect is unbiased

Question 10. How should an odds ratio of 2 be described for a common outcome? A. Exactly twice the risk in every populationB. An absolute increase of 2%C. Proof of causationD. Twice the odds, not automatically twice the risk

0 / 10 answered

References & Further Reading

Use the full methods and relevant chapters when appraising a paper. These sources support further study; the examples and questions above are original teaching exercises.

Reference review: 25 September 2026. Consult current institutional guidance for project approval and clinical decisions.