Watson-Glaser for Public Health ST1: the five sections and how to practise

Last updated 9 October 2026

The Watson-Glaser is the first paper you sit at the Public Health ST1 assessment centre, and the one most applicants have never met before. This page explains the five sections using the publisher's own directions, then gives two practice questions with explanations.

Pearson VUE describes the paper as the Watson-Glaser Critical Thinking Appraisal, UK Edition: 40 questions in 30 minutes, which is 45 seconds a question. It starts the day on 5 or 6 January 2027 and NHS England says the RANRA follows it immediately, with no pause. The questions are not about public health. They test whether you can reason from a passage without adding what you already believe, which is exactly the skill a registrar needs when reading a report or a consultation response.

The five sections

The publisher's practice booklet, which Pearson VUE hosts for applicants, describes five tests. Each has its own directions and its own answer options, and the directions change what counts as a correct answer. The official material does not say how the 40 questions are divided between the sections, so prepare for all five.

1. Inference

You are given a statement of facts to regard as true, followed by proposed inferences. For each one you choose: True, Probably True, Insufficient Data, Probably False or False. "True" means the inference follows beyond reasonable doubt from the facts. "Insufficient Data" means the facts give no basis for judging either way. The directions note that deciding between probably true and probably false sometimes needs commonly accepted knowledge that practically everyone has. This is the only section where outside knowledge is allowed in, and only in that limited way.

2. Recognition of assumptions

A statement is followed by proposed assumptions. You decide whether each one is made in the statement, meaning taken for granted whether justifiably or not, or not made. The booklet's example is "We need to save time in getting there so we'd better go by plane." That assumes a plane is faster and that a plane service exists. It does not assume a plane is more convenient, because the statement says nothing about convenience.

3. Deduction

Several premises are followed by proposed conclusions. You treat the premises as true without exception and decide whether each conclusion necessarily follows. The directions warn you to ignore what you believe from general knowledge and to stick to the statements. They also define "some": it means at least a portion, and perhaps all, of a class. "Some holidays are rainy" could mean every holiday is rainy.

4. Interpretation

A short paragraph is followed by conclusions. Everything in the paragraph is true, and you decide whether each conclusion follows beyond a reasonable doubt. This is a lower bar than deduction's "necessarily follows", which is the main difference between the two sections. A conclusion can be interpretation-correct even if a strict logician could construct an exception.

5. Evaluation of arguments

A question is followed by arguments for or against. You treat each argument as true and decide whether it is strong or weak. Strong means both important and directly related to the question. Weak means not directly related, of minor importance, or about a trivial aspect. Your own view on the question is irrelevant. The directions also fix the meaning of "should" in these questions: would the proposed action promote the general welfare of the people in the United Kingdom?

Practice question 1: inference

Practice question 2: recognition of assumptions

Both questions come from our Full Test 2, which uses UK public health passages throughout. The real paper may use any subject matter, and the reasoning rules are the same whatever the topic.

How to prepare

Learn the directions by heart. On test day each section begins with directions you have already read many times, and the 30 minutes are better spent on questions. Know the answer options for each section before you walk in.

Treat "necessarily" and "beyond reasonable doubt" as different tests. Deduction asks whether a conclusion must be true given the premises. Interpretation asks whether it is true beyond reasonable doubt. The same conclusion can fail the first and pass the second.

Watch for "some" and "all". In the deduction section "some" can mean all. In inference, a statement about a group average says nothing certain about any individual member of the group.

Keep your opinions out of the room. In evaluation of arguments you may privately disagree with every "strong" argument you mark. The question is whether the argument, taken as true, bears directly and importantly on the question.

Work at 45 seconds a question. Nobody has time to re-read a passage three times. Read it once carefully, then work through the items on it. If you are stuck, choose, move on, and come back if time allows.

The other two papers are covered in our RANRA guide and SJT guide. All the 2027 dates are on the timeline page.

Frequently asked questions

Sources

• Pearson VUE: Watson-Glaser Critical Thinking Appraisal UK Edition practice test (PDF)
• Pearson VUE: Public Health National Recruitment Office tests
• NHS England Medical Hub: Public Health assessment centre