Watson–Glaser Inference guide
Watson–Glaser Inference gives you a passage of assumed-true facts and asks you to grade a proposed inference on a five-point scale — True, Probably True, Insufficient Data, Probably False, False — judged strictly from the passage.
The method
- Treat the passage as true and ask how strongly it supports the inference.
- Learn the five grades as bands of probability, and where their boundaries sit.
- Grade from the passage only — not from what you know about the world.
- Use Insufficient Data when the passage genuinely does not lean either way, not as a safe default.
How to use the Watson-Glaser inference scale
Treat the five labels as evidence strengths, not confidence feelings. True and False require the passage to settle the claim. Probably True and Probably False apply when the stated facts lean clearly in one direction without settling it. Insufficient Data belongs in the middle when the passage gives no defensible lean.
Break the inference into subject, quantity, time and claim. A passage may settle the number of respondents while saying nothing about all employees, or establish what happened last year while leaving the present open. Grade the whole inference at the strength of its weakest unsupported part.
Final check before you answer
- Use the exact population named in the inference.
- Reserve True and False for claims the stated facts settle.
- Use Insufficient Data only when the evidence does not lean either way.
Worked method example: keep the population fixed
Original teaching example. It is not a live provider question or a premium bank item.
Of the 40 employees invited to a survey, 32 responded. Twenty-four respondents preferred remote training.
Task: Grade the inference: Most respondents preferred remote training.
Answer: True.
Why: Twenty-four of 32 respondents is three quarters, so the passage settles that more than half of the respondents preferred remote training.
Strongest trap: Do not extend the finding to most employees in the company. The passage gives no company headcount or view from employees outside the respondent group.
Common mistakes
- Grading from world knowledge instead of the passage.
- Confusing 'Probably True' with 'True' on a directly stated fact.
- Defaulting to Insufficient Data whenever you feel unsure.
- Sliding one grade too strong or too weak on the scale.
Frequently asked questions
When is it True versus Probably True?
True is reserved for what the passage establishes beyond reasonable doubt; Probably True is the right grade when the passage makes it likely but not certain.
Practise this now
Preview the question styleOpen the drill
Watson-Glaser guide and rehearsal availability
Editorial responsibility: Alexander Torstensson. See the verification and corrections process.