Compare methods of measuring pain
Compare clinical interviews, the McGill Pain Questionnaire, visual analogue scales and behavioural observation, then use Brudvik et al. to evaluate child, parent and physician ratings.
Original StudyForA teaching mapped to Cambridge 9990 Health Psychology sections 3.3.1–3.3.3, 2028–2030 Version 1. Example studies illustrate a topic and are not official Cambridge materials or mark schemes. This is psychology education, not pain diagnosis or treatment advice.
Before you begin
- This lesson covers Cambridge Psychology 9990 Health Psychology section 3.3.2. Self-report, interviews, psychometric scores and behavioural observations provide related but distinct evidence.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What did Brudvik et al. (2016) actually compare?
What you will learn
- Subjective measurement and clinical interview
- McGill Pain Questionnaire and visual analogue scale
- Doctor/parent/child pain assessments; Brudvik et al. (2016)
- UAB pain behaviour observational scale
Pain measurement needs to match the question
Pain is a personal sensory and emotional experience. A researcher or practitioner cannot directly read it from a scanner or an observer’s impression. Measurement therefore uses reports, ratings or behaviour as indicators of parts of the experience. Each method answers a different question and carries its own assumptions.
A clinical interview can ask about location, quality, timing, context, interference with activities and the person’s own explanation. Open questions can provide detailed qualitative and idiographic information; structured questions can make answers more comparable. Interviews depend on recall and language, and the interviewer’s wording, relationship and assumptions can influence responses. Accessibility and a person’s preferred way to communicate matter.
A psychometric questionnaire applies consistent prompts and scoring. Standardisation can support comparisons and reliability, but a score is not the experience itself. Translation, age, literacy, culture, setting and whether the items capture what matters to the person can affect validity.
McGill Pain Questionnaire and visual analogue scales
Melzack’s McGill Pain Questionnaire asks respondents to select descriptors of their pain. Its major score outputs include a Pain Rating Index based on chosen words, the number of words selected and a present-pain-intensity rating on a 1–5 scale. The descriptors can represent sensory, affective and evaluative aspects, offering more detail than a single intensity number.
The McGill measure may help describe the quality and dimensions of reported pain, but it depends on language, comprehension and the available descriptors. A selected word does not prove a biological mechanism. Comparisons are only meaningful when the measure is appropriate for the population and used consistently.
A visual analogue scale (VAS) commonly asks a person to mark a point on a line anchored by descriptions such as ‘no pain’ and ‘worst pain imaginable’. The distance along the line is converted into a quantitative score. A simple line can be quick and sensitive to change, but it assumes the line represents a meaningful continuum. Vision, motor control, age, instructions and endpoint interpretation can affect use. A VAS compresses a complex experience into one dimension and should not automatically stand in for quality, function or distress.
Brudvik et al. (2016) compared three perspectives in one emergency department
Brudvik, Moutte, Baste and Morken studied 243 children aged 3–15 who attended Bergen Accident and Emergency Department in Norway in 2011. The cross-sectional study compared children’s age-adapted pain ratings with independent numeric ratings by their parents and physicians. It examined agreement at one assessment in one setting, not a trial of an assessment or treatment.
Mean ratings were 5.5 from children, 4.8 from parents and 3.2 from physicians. Agreement was moderate between children and parents (weighted κ = .55) and low between children and physicians (κ = .12) and parents and physicians (κ = .17). The authors reported that physicians underestimated pain in this sample. These group results do not show that every physician underestimates every child or that parent and child ratings always agree.
The key lesson is to separate reporters and methods: children used age-adapted scales, while parents and physicians provided their own numeric ratings. The paper does not mean that every child completed a visual analogue scale. It shows why self-report, when a child can provide it using a suitable method, should not be replaced by an adult guess. The results come from one Norwegian emergency department in 2011 and may not generalise to every clinical or cultural setting.
Observation complements self-report; it does not replace it
The UAB Pain Behavior Scale was designed as a rapid observational measure that different members of a pain team could use, with initial work on reliability and validity. An observation can record visible behaviours consistently, and agreement between observers can be studied. Behaviour is not a direct measure of a private experience: people differ in expression, may conceal pain, and may be unable to communicate in familiar ways.
A low observed-behaviour score therefore does not prove that pain is absent or mild. Conversely, a behaviour score should not be interpreted as a diagnosis. The measure was developed in chronic-pain contexts; its original purpose and population matter when considering transfer to children, acute injury or another setting.
Triangulation means using complementary sources, such as an interview, a suitable self-report scale and observation, while keeping their results distinct. Agreement can strengthen confidence that several indicators point in a similar direction; disagreement is useful information to explore rather than a reason to discard the person’s report.
Choose measures and claims with validity in mind
Idiographic evidence asks about one person’s experience in depth; nomothetic evidence compares patterns across people. Qualitative interview responses can explain meanings, while ratings provide quantitative scores. Neither type is inherently better: validity depends on whether the method measures the question being asked.
A reliable score is produced consistently, but consistency alone does not establish that it captures pain. A valid measure must fit the construct, age group, language and context. Generalisations should be limited to populations and settings supported by the evidence; observer ratings, parent ratings and child self-reports are separate measures, not interchangeable readings of one objective quantity.
Sources for this lesson
- Cambridge International AS & A Level Psychology 9990 syllabus, 2028–2030
- Cambridge International AS & A Level Psychology 9990 Reference List, 2028–2030
- Brudvik et al. (2016), A comparison of pain assessment by physicians, parents and children in an outpatient setting
- Melzack (1975), The McGill Pain Questionnaire: major properties and scoring methods
- McGill University Alan Edwards Centre for Research on Pain: McGill Pain Questionnaire
- Richards et al. (1982), Assessing pain behavior: the UAB Pain Behavior Scale
- IASP pain terminology
Pause and explain
What does the UAB Pain Behavior Scale primarily record?
Worked example
A clinic uses a UAB observation score to overrule a child’s report because the child appears calm. Evaluate this decision using the syllabus measures.
Show the worked solution
- Distinguish a child’s self-report from an observer’s record of visible behaviour.
- Use Brudvik et al. to explain why child, parent and physician ratings may differ without treating its sample as universal.
- Recommend interpreting suitable complementary measures together and checking communication needs rather than inferring absence of pain.
Answer The observation scale can record behaviour consistently, but behaviour is not the pain experience itself and a calm appearance cannot establish that pain is absent. Brudvik et al. found low child–physician agreement in one Norwegian emergency department sample, although that result cannot be applied to every child or clinician. A suitable child self-report, interview, observer record and contextual information should be kept distinct and interpreted with the child’s age and communication needs in mind.
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 researcher wants detailed descriptions of pain quality and also needs to track intensity ratings over several visits. Select two complementary measures and explain one limitation of each.
Give me a hint
Pair a descriptive interview or questionnaire with a repeated rating, and keep each measure’s construct clear.
Compare my reasoning
- A clinical interview can explore quality, timing and impact in the person’s own words.
- The McGill questionnaire can structure descriptor choices; a VAS can provide a separate intensity score.
- Explain that language or interviewer effects can shape descriptions and a single line score omits other dimensions.
A clinical interview or McGill descriptor measure can describe how pain is experienced, while repeated VAS ratings can track one dimension of reported intensity over time. Interviews depend on language, recall and interaction; the VAS depends on suitable instructions and assumes a meaningful line continuum. The scores answer different questions and should not be treated as interchangeable.
Look for these in your work
- Measures matched to distinct aims
- One limitation per method
- Constructs kept separate
Use the Brudvik study to explain why parent and physician ratings should not be substituted automatically for a child’s own report.
Give me a hint
Name the sample, compare the mean ratings, and avoid claiming that one study represents every child.
Compare my reasoning
- The cross-sectional study included 243 children aged 3–15 in one Norwegian emergency department in 2011.
- Mean pain ratings were 5.5 for children, 4.8 for parents and 3.2 for physicians; child–physician agreement was low.
- Report the result as evidence from that sample and note that reporters used distinct rating methods.
In Brudvik et al.’s 243-child sample, the mean child rating (5.5) exceeded the parent rating (4.8) and physician rating (3.2), with low child–physician agreement. This supports listening to the child’s suitable self-report rather than assuming an adult score is equivalent. The finding is bounded to one cross-sectional setting and does not show that every adult underestimates every child.
Look for these in your work
- Correct sample and setting
- Ratings and agreement described
- No universal claim
A study finds a strong correlation between an observer’s behaviour score and a patient’s VAS rating. Give one useful conclusion, one limit and a follow-up measure.
Give me a hint
Association can support converging evidence but cannot show that either measure is the whole experience or causes the other.
Compare my reasoning
- The measures covary in the sampled context, which may provide evidence of association between two indicators.
- A correlation does not show that the observation causes pain or that the VAS and behaviour score measure identical constructs.
- Add an accessible interview or repeated ratings and describe the sample, setting and reliability of observers.
The association suggests that observed behaviour and self-reported intensity varied together in that sample. It does not prove that they measure the same aspect of pain, that behaviour causes pain, or that an observer can infer an individual’s experience. An accessible interview and repeated measures could add context; observer training and a varied sample would help assess reliability and generalisability.
Look for these in your work
- Association stated accurately
- Causal/construct limits identified
- Relevant complementary method proposed
Common mistakes
- Calling every pain scale an objective measurement of the experience
- Treating VAS and numeric ratings as the same instrument
- Claiming Brudvik et al. used a VAS for every child or that it was a treatment trial
- Generalising one emergency department’s mean ratings to all clinicians and families
- Using an observation score as proof that pain is absent or exaggerated
- Confusing reliability (consistency) with validity (measuring the intended construct)
What can you explain now?
Why should a UAB Pain Behavior Scale score not replace a child’s suitable self-report?
Compare with the explanation
The scale records observable behaviour, not the whole personal experience; people express pain differently, so a low behaviour score cannot prove absence of pain.
Complementary measures can disagree and still each provide useful but partial information.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Compare one subjective pain measure with one observational measure. State what each records and why neither is a complete objective reading of pain.
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.