How personality is measured, what the alternatives offer, and how test use is governed
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Key idea Personality tests serve research and applied practice, and using them to diagnose is governed in the UK.
Personality inventories (scales and similar instruments) are typically used in research, but also in applied practice.
Instruments can be proprietary, or well understood and free to use. Using tests to diagnose is governed in the UK, and ethics considerations are important.
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Validity asks whether a measure is measuring what we think it is.
Takeaway The three kinds of validity ask whether a measure covers its scope, is well structured and is predictive.
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Classical test theory (CTT) is an approach to scale or test development that acknowledges error. Check what each part of its equation stands for.
The CTT equation
= ±
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The observed score, on the left-hand side of the equation.
The true score. The observed score equals this, plus or minus error.
The error that CTT acknowledges.
The observed score equals the true score plus or minus error. CTT uses a pool of items that reliably measures the same latent idea in a homogenous group, and the items should discriminate.
Takeaway CTT treats every observed score as a true score plus or minus error.
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Administration, scoring and norms are all standardised. (known comparison-group scores used to place an individual's score) What do norms make possible?
Norms facilitate standardised interpretations. Standardised procedures are documented in a Test Manual, and standardised norms are developed as percentiles.
Takeaway Norms support standardised interpretation of scores.
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Interviews are an alternative to personality scales. How do they vary in standardisation and structure?
Interviews
Degrees of standardisation / structure
Interviews range from standardised to unstructured or free-form. Standardised interviews are non-psychodynamic and yield explicit data; free-form ones are psychoanalytic, with freedom to explore.
Takeaway Interviews vary in standardisation, and few structured personality interview tools exist.
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Psychoanalytic approaches aim to get under the hood. What do proponents of projective methods argue about quantitative personality tests?
They argue the methods avoid distortions and biases associated with quantitative personality tests. The aim is to measure implicit characteristics.
Takeaway Proponents argue projective methods avoid the distortions and biases they associate with quantitative tests.
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Lilienfeld and colleagues (2000) suggest ascientific and inadequate evidence to support validity. Try each point before revealing it.
Inter-rater reliability is problematic, and practitioners may draw different inferences.
Prediction from projective methods is inadequate.
There is no incremental validity over and above cheaper methods, which raises the question of ethics.
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Key idea Test use is governed by three qualification levels, and the specialist level is occupational only.
The BPS governs test use. These are its qualification levels.
Put these in order, then check.
Steps run in this order.
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Often from many thousands of participant responses. An individual's score is placed relative to known comparison groups.
Random, representative and incidental or opportunistic sampling are listed, along with bias.
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They are time consuming, and reliability is a question mark.
Richer multi-source data: overt responses, and less overt responses such as intonation, facial expressions and mannerisms.
In clinical settings, for example reliable diagnosis of PDs and treatment.
Social presentation, and bias such as self-fulfilling prophecy during interview and related assessment.
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Information and services on standards for test takers, users, developers and the general public. A register of qualified test users is maintained.
Maintaining skills and competence is a requirement to remain registered.
Educational: strengths and learning needs. Forensic: reoffending risk assessment. Occupational: selection, career development, guidance and advice.
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Introduction to testing, administering tests to one or more candidates in two parts, and maintaining security and confidentiality of test materials and data.
Scaling and standardisation, norm-referenced interpretation, and classical test theory and reliability appear in every Test User route listed.
Personality, personality assessment and influences on personality are listed for the Occupational personality route.
Approaches to testing and test construction; reliability, validity and utility issues; computer-based assessment and reports; identifying assessment needs; and when and how to use tests.
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An internationally recognised qualification and entry on the Register of Qualifications in Test Use as a BPS Registered Test User. It also brings online access to over 160 tests, otherwise restricted, plus CPD resources and CIPD training course discounts.
Developing and selecting appropriate tests; administering and scoring tests; reporting and interpreting test results; and informing test takers.
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