Individual Differences - Chapt 23 | Psychometrics: Reliability & Validity

What’s the difference between reliability and validity?

Reliability = consistency; Validity = accuracy.

What is a psychometric test?

A standardised instrument to measure a psychological construct.

Name three types of reliability.

Test–retest; internal consistency; inter-rater.

Which statistic measures internal consistency?

Cronbach’s alpha (α).

How can a test be reliable but not valid?

It gives consistent but wrong results (e.g., “memory” test that’s really spelling).

What is convergent validity?

Correlation with related constructs (e.g., vindictiveness ↔ spitefulness).

What is discriminant validity?

Lack of correlation with unrelated constructs (e.g., vindictiveness ≠ agreeableness/Big Five).

How is predictive validity tested?

Check whether scores forecast future behaviour or outcomes.

What is concurrent validity?

Agreement with another established test measured at the same time.

What is criterion-related validity?

Correlation with an external criterion/benchmark.

What is face validity?

Measure looks appropriate “on the face of it.”

What is content validity?

The test covers all key domains of the construct.

What is a multitrait–multimethod matrix?

Grid comparing multiple traits across methods to evaluate construct validity.

How was the EPDS validated (Cox et al., 1987)?

Scores linked to clinical judgements of postnatal depression.

Why is content validity crucial in scale design?

Ensures all aspects of the construct are represented.

Name two ethical concerns in psychometric testing.

Potential misuse/cultural bias; labelling/stigma.

How do psychometric tests relate to reductionism?

They compress complex behaviour into numerical scores.