Evaluate evidence in a source-based response
Explain what evidence supports, assess its method and limitations, and avoid judging a source by its conclusion alone.
Section CONTEXT-25 · Optional global topic · Migration and work
Exam scope and assessment notes
This is original StudyForA teaching and fictional practice, not Cambridge text, an official question or an official mark scheme. The 2026–2028 syllabus calls the written exam Component 1; the 2029–2031 syllabus calls it Paper 1 and reports no significant teaching changes. Check the syllabus for the learner's exam year and follow teacher, centre and assessment-authenticity rules. StudyForA cannot authenticate assessed work, observe collaboration, award official marks or predict a grade.
Before you begin
- Identify whether the task concerns source analysis, essay writing, team assessment or the independent research report.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which evaluation is most useful?
What you will learn
- Select evidence relevant to a claim
- Explain a strength and limitation of source evidence
- Reach a reasoned evaluation within the source's scope
Match evidence to the claim
A longer response about one source should explain how the evidence supports or weakens a claim. Identify what was measured, who or what was included, the time and place, and the reasoning from observation to conclusion. A number is not automatically strong evidence.
Evaluate specifically
A useful evaluation explains why a feature matters. For example, a recent survey of service users may help describe those users' experience but exclude non-users. State what the method permits, what it cannot establish and what evidence could test the gap.
Sources for this lesson
- Cambridge International AS & A Level Global Perspectives & Research 9239 syllabus · 2026–2028 Version 3
- Cambridge International AS & A Level Global Perspectives & Research 9239 syllabus update · 2026–2028
- Cambridge International AS & A Level Global Perspectives & Research 9239 syllabus · 2029–2031 Version 1
- Cambridge International 9239 subject page and exam-series notice
Pause and explain
A survey includes only current service users. Which limitation is most relevant?
Worked example
A source claims a new park improved wellbeing after surveying 32 visitors on opening weekend. Evaluate how far this evidence supports the claim.
Show the worked solution
- State what the survey directly records.
- Explain why opening-weekend visitors may not represent all residents or long-term effects.
- Conclude what the evidence supports and what additional evidence would help.
Answer The survey records the views of 32 people who visited on opening weekend, so it can suggest how those respondents felt at that time. It may miss non-visitors and cannot show whether wellbeing changed over time or because of the park. Follow-up evidence from a broader sample and a baseline would strengthen the claim.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A source reports that 72% of 25 volunteers liked a new timetable. Evaluate one strength and two limits for the claim that all students prefer it.
Give me a hint
Keep the response count, selection method and population claim in view.
Compare my reasoning
- State what the result directly says.
- Explain how the voluntary sample limits representativeness.
- Name another source or method needed for the whole-school claim.
The result directly shows that 72% of the 25 volunteers who replied liked the timetable. The small self-selected group may differ from students who did not volunteer, so it cannot establish the preference of all students. A broader, clearly sampled survey and a record of non-response would be needed.
Look for these in your work
- States the observed result precisely
- Explains the selection limitation
- Names evidence for the wider claim
A source uses one year's average temperature to claim a local policy reduced heat risk. What does that evidence not establish by itself?
Give me a hint
Consider what would be needed to connect a local policy to the measured outcome.
Compare my reasoning
- Identify the observed measure and time period.
- Ask whether the data are local and comparable before and after the policy.
- Name other influences or a stronger comparison.
One annual average alone does not show that the policy caused a reduction. Check whether the measure is local, whether comparable earlier data exist and whether weather or measurement methods changed. A suitable comparison over time or with a similar area could help, though other influences may remain.
Look for these in your work
- Separates observation from cause
- Checks place and baseline
- Names a comparative method
A source's chart excludes its two months with the highest reported costs. Explain how this affects a claim that the policy stayed affordable.
Give me a hint
Describe the direction of the missing evidence and why the omission matters.
Compare my reasoning
- State what data are missing.
- Explain how the missing months relate to the affordability claim.
- State what a complete series would allow the reader to assess.
Excluding the two highest-cost months removes evidence that could challenge the affordability claim. The remaining chart may understate variation or peak costs. The full series, the reason for exclusion and a consistent cost definition are needed before judging affordability.
Look for these in your work
- Identifies the omission
- Connects it to the claim
- Names the evidence needed
Common mistakes
- Calling a source reliable or biased without explaining why
- Confusing the source's sample with the population in its conclusion
- Claiming causation from a single short-term observation
What can you explain now?
Which evaluation is most useful?
Compare with the explanation
It links a method feature to what the source can and cannot show.
Evaluation explains why evidence is strong or limited for the claim.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
How does an evaluation connect a method limitation to a claim?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.