Assess evidence credibility
Distinguish source reliability, content plausibility and independent corroboration when assessing a claim.
Original StudyForA scenarios and formative model answers; no Cambridge marks, predicted grades or certified mastery. Alternative reasoned answers may be valid. Full-length unseen papers, a wider mixed-problem bank and calibrated specialist teacher marking remain outstanding.
Before you begin
- Read an English passage closely
- Distinguish a statement from its supporting reason
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Before evaluating support, what should you identify?
What you will learn
- Apply relevant credibility criteria to specific evidence
- Distinguish consistency from corroboration and contradiction
Explain the criterion in context
Ask what a source could observe, what relevant expertise it has, whether it has a reliable record, and what interests or bias might influence its report. A witness behind an obstructed window may have poor ability to see, even with a good reputation. A shop owner benefits from selling a product, which gives a reason for caution about promotional claims, not proof that the claims are false.
Assess the content too: does the claim fit known constraints, or require an extraordinary unexplained event? Plausibility and source reliability are separate. An expert outside their field is not automatically an expert on this question.
Compare evidence without counting copies
Corroboration provides additional support; consistency merely means two statements can both be true. ‘The shop opened before nine’ and ‘I arrived at ten’ are consistent but the second does not establish the opening time. Independent records of an 08:55 opening can corroborate one another.
Several reports copied from one press release are not several independent confirmations. Explain the effect of an interest, access limitation or agreement on this specific claim, and make a qualified assessment rather than ranking people as universally trustworthy or untrustworthy.
Sources for this lesson
Pause and explain
Do two websites copying one supplier release give independent corroboration?
Worked example
A fictional supplier says its battery lasts ten hours; an independent laboratory reports six hours under a stated heavy-load test. Assess the apparent conflict.
Show the worked solution
- The supplier has a sales interest.
- The laboratory has relevant testing expertise and gives conditions.
- The claims may use different loads, so check conditions before calling them contradictory.
Answer The supplier’s interest warrants caution, while the laboratory’s transparent method supports its six-hour result under heavy load. The two figures need not contradict if test conditions differ; matched conditions are needed for a direct comparison.
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.
Guided: Explain a strength and a limitation of the laboratory battery evidence.
Give me a hint
Use access, expertise and the stated test conditions.
Compare my reasoning
- Testing expertise supports competence.
- A specified heavy-load method is transparent.
- The result may not apply to light use.
The laboratory has relevant expertise and provides test conditions, supporting the heavy-load result. Its six-hour figure is still condition-specific and does not establish battery life under every type of use.
Look for these in your work
- Uses a contextual criterion
- Explains its effect
- States the limit
Independent: A witness says a vehicle was blue but viewed it at night through tinted glass. Assess this particular colour claim.
Give me a hint
Focus on ability to observe rather than honesty alone.
Compare my reasoning
- Night lighting can affect perceived colour.
- Tinted glass changes the view.
- Seek independent colour evidence.
The colour identification is weakened by limited viewing conditions, even if the witness is honest. Daylight footage or another well-positioned witness could improve confidence; the limitations do not prove the vehicle was not blue.
Look for these in your work
- Names the observation limits
- Explains relevance
- Avoids an unsupported reversal
Application: Source A says a venue opened at 08:55. B says it was open at 09:10. C provides an independent timestamped opening record at 08:55. Compare consistency and corroboration.
Give me a hint
A later open state is not the same as an opening time.
Compare my reasoning
- B can be true alongside A.
- B does not establish 08:55.
- C independently supports A’s precise time.
B is consistent with A but does not corroborate its precise opening time. If authentic and independent, C corroborates A. The strength of that support still depends on the record’s accuracy and what its timestamp actually records.
Look for these in your work
- Distinguishes consistency
- Identifies corroboration
- Checks the evidence meaning
Common mistakes
- Treating an interest as proof of lying
- Counting copied reports as independent
- Calling consistent statements corroboration
What can you explain now?
Do two websites copying one supplier release give independent corroboration?
Compare with the explanation
No, their evidence has a common origin
Independence concerns how the evidence was obtained, not the number of publications.
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Make it stick
Do two websites copying one supplier release give independent corroboration?
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.