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 07 / 20

Probability, Standard Error & Confidence Intervals

Separate variation among people from uncertainty about an estimate, and interpret intervals without overclaiming.

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

Question 01. An independent sample has SD 10 and n = 100. What is the estimated SE of its mean? A. 10B. 1C. 100D. 0.01

Question 02. If sample size increases fourfold with similar independent variation, what happens to SE? A. It doublesB. It approximately halvesC. It becomes exactly zeroD. It stays four times larger

Question 03. What does a 95% confidence-interval procedure promise under its assumptions? A. 95% of patients lie inside every intervalB. A 95% chance that every hypothesis is correctC. About 95% coverage across repeated samplesD. Absence of all bias

Question 04. Compared with a 95% interval, a 99% interval from the same method and data is usually what? A. NarrowerB. Always identicalC. WiderD. Necessarily centred at zero

Question 05. Which quantity describes uncertainty in an estimated mean? A. The raw maximum aloneB. The recruitment postcodeC. The number of categories aloneD. Standard error

Question 06. Can a very narrow confidence interval still be misleading? A. No, narrowness eliminates biasB. Only when the sample is one personC. Yes, if the estimate is systematically biasedD. No, precision guarantees validity

Question 07. Mean 50 and SE 1 give what approximate normal 95% interval? A. 48.04 to 51.96B. 40 to 60C. 49.99 to 50.01D. 0 to 100

Question 08. Which probability is sensitivity? A. Positive test given diseaseB. Disease given positive testC. Disease given negative testD. Negative test given no disease

Question 09. Why is a confidence interval for a mean unsuitable as an individual prediction interval? A. Every patient equals the meanB. Sample size removes individual variationC. Individual variation adds uncertainty beyond estimating the meanD. A mean cannot be estimated

Question 10. An interval contains both worthwhile benefit and harm. What is the best interpretation? A. The effect is too imprecise for a firm directional conclusionB. The treatments are proven equivalentC. There is definitely no effectD. Harm is impossible

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.