Psychological Assessment and Testing
Psychological assessment and testing is the area of clinical psychology concerned with gathering, measuring, and integrating information about a person's cognition, emotion, personality, and behaviour in order to answer a referral question. It spans standardized tests, structured interviews, observation, and the measurement theory that lets scores be interpreted defensibly.
Definition
Psychological assessment is the systematic process of collecting and integrating information about a person, often through standardized tests, interviews, observation, and records, to describe functioning and answer a referral question; testing is the narrower act of administering a standardized instrument and deriving scores.
Scope
This area orients the reader to how clinical psychologists obtain and interpret information about people: the psychometric foundations of measurement, the diagnostic interview, the assessment of cognitive ability, the measurement of personality, and the direct observation and functional analysis of behaviour. It treats assessment as a methodological and conceptual domain, describing how evidence about a person is generated and appraised rather than prescribing tests or clinical actions for any individual.
Sub-topics
Core questions
- What information answers the referral question, and which methods yield it reliably?
- How do reliability and validity govern what a test score can and cannot support?
- When should clinical judgement be combined with, or deferred to, statistical (mechanical) prediction?
- How are scores interpreted fairly across people from different backgrounds?
Key concepts
- Reliability and measurement error
- Validity (content, criterion, construct)
- Standardization and norms
- Referral question and integration
- Test fairness and bias
- Clinical versus mechanical (statistical) prediction
Key theories
- Construct validity
- Cronbach and Meehl argued that when a test measures an attribute not defined by a single operation, evidence for the inferred construct must be accumulated through a nomological network linking the test to other observable variables; this reframed validation as theory testing rather than simple criterion correlation.
Mechanisms
Assessment proceeds from a referral question to the selection of methods, the controlled collection of responses, the conversion of responses into scores against norms, and the integration of multiple data sources into an interpretation. Psychometric theory supplies the warrant for each step: reliability indexes how much of a score is signal rather than error, and validity, framed by Cronbach and Meehl as construct validity and elaborated by Messick as a unified, argument-based concept, governs whether the intended inference is justified. Grove and colleagues' meta-analytic comparison of clinical and mechanical prediction shows that how data are combined, not only how they are collected, affects accuracy.
Clinical relevance
Assessment underlies case formulation, diagnostic classification, treatment planning, and outcome monitoring across clinical psychology, and critical appraisal of test evidence is part of competent practice. This entry describes the logic and standards of assessment as a field; it is reference-educational and is not a protocol for selecting, administering, or interpreting tests for any individual.
Evidence & guidelines
The Standards for Educational and Psychological Testing, issued jointly by the AERA, APA, and NCME, are the consensus reference for the development, evaluation, and use of tests and frame validity, reliability, and fairness as shared professional expectations. Messick's unified account of validity and Grove and colleagues' meta-analysis on prediction are widely cited methodological anchors for the area.
History
Modern psychological testing grew from late nineteenth- and early twentieth-century work on individual differences and intelligence, and consolidated as classical test theory through the mid-twentieth century. Cronbach and Meehl's 1955 paper on construct validity reoriented the field toward theory-based validation, and Messick later unified the validity concept around the justification of score inferences and their consequences. Meehl's earlier work on prediction seeded a long line of research, summarized meta-analytically by Grove and colleagues, on how clinical and statistical methods of combining data compare.
Debates
- Clinical versus mechanical prediction
- A durable question is whether clinicians' integrative judgement outperforms simple statistical rules; meta-analytic evidence generally favours mechanical combination of the same data, while debate continues over scope, data quality, and the role of expert judgement in selecting predictors.
Key figures
- Lee Cronbach
- Paul Meehl
- Samuel Messick
Related topics
Seminal works
- cronbach-meehl-1955
- messick-1995
- grove-2000
Frequently asked questions
- What is the difference between assessment and testing?
- Testing is administering a standardized instrument and deriving scores; assessment is the broader process of collecting and integrating information from tests, interviews, observation, and records to answer a referral question.
- Why do reliability and validity matter so much in this area?
- Reliability sets a ceiling on how trustworthy a score can be, and validity determines whether the inference drawn from the score is justified; without both, an interpretation cannot be defended.