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 04 / 20

Sampling & Generalisability

Distinguish selecting a sample from assigning treatment, and judge whose experience the results actually represent.

Choose an answer and check it immediately. Change your choice to try again. This is a self-study exercise; results are not saved.

Question 01. What is a sampling frame? A. The final confidence intervalB. The treatment allocation sequenceC. The practical list or source from which a sample is selectedD. The journal’s reviewer list

Question 02. Which process is random sampling? A. Assigning enrolled patients to treatments by chanceB. Measuring outcomes blindlyC. Selecting people from a population by chanceD. Alternating treatment by admission date

Question 03. Why may a very large convenience sample remain biased? A. Sample size always removes selection biasB. Systematic exclusion may persistC. Every participant becomes independent automaticallyD. Precision and representativeness are identical

Question 04. Selecting villages first and residents within them is an example of what? A. A case reportB. Cluster samplingC. Allocation concealmentD. Individual simple randomisation to therapy

Question 05. What is a reason to use stratified sampling? A. Ensure sampling within important population subgroupsB. Eliminate every measurement errorC. Guarantee a causal treatment effectD. Replace eligibility criteria

Question 06. Which threatens external validity most directly? A. A well-defined primary outcomeB. Transparent eligibility criteriaC. Complete reporting of recruitmentD. Applying a specialist-centre result to a very different care setting

Question 07. What does internal validity primarily concern? A. Credibility of the comparison within the studyB. The number of countries in the titleC. The popularity of the journalD. Whether every possible patient was included

Question 08. Why examine non-responders in a survey? A. Every non-response is randomB. Participation may relate to the outcome of interestC. Non-response automatically increases accuracyD. Responders cannot differ from non-responders

Question 09. What is consecutive recruitment? A. Selecting only the easiest five patientsB. Assigning treatment by coin tossC. Sampling only people with a positive testD. Inviting all eligible attenders during a specified period

Question 10. What happens if positive within-cluster correlation is ignored? A. Every effect estimate becomes exactly zeroB. Uncertainty may be underestimatedC. All confidence intervals necessarily widenD. Selection bias disappears

0 / 10 answeredReady for assessment →

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.