P+I: Psychometrics

What are Psychometrics?

Measures designed to assess differences among people in terms of abilities, attributes, and characteristics. Also deals with the design, administration, and interpretation.

Who was Francis Galton?

• Darwin’s cousin

• Studied intelligence functioning and whether it was inherited

• Father of eugenics

• First lab for psych testing

Why study psychometrics?

Theory testing & the scientific method

What is a Psychological Test?

A measurement device/technique that uses systematic procedures to quantify behaviour or to help in the understanding & prediction of behaviour

Types of Psychometric tests?

Ability tests, personality tests, projective tests, and objective tests

What are ability tests?

Tests that measure cognitive abilities such as recall, reasoning, problem solving

What are personality tests?

Tests that measure traits and behaviours that will shape how an individual interacts with the world around them

What are projective tests?

Indirect measures of an individual’s mental state (e.g. inkblots)

What are objective tests?

Tests that measure behaviours in a standardised setting aka “miniature situation” (e.g. stroop test)

What are the properties of tests?

Normative Referenced (summary of test results for a large and representative group standardization sample or the group norm) and Criterion Referenced (pre-set standard for acceptable performance)

What is validity?

How accurate the measure is at measuring what its supposed to

How are validity and reliability related?

Low reliability always means low validity

High reliability does not always mean high validity

What is face validity?

Assesses whether the test appears to measure what it is supposed to measure (related to perceived purpose of the test).

What is content validity?

Assesses whether the test covers all the relevant parts or the “content” of the domain it is designed to measure.

What is construct validity?

Assesses whether the test is demonstrating a relationship between the concept at a theoretical level and the measure that has been developed.

• Convergent (agrees with other tests)

• Divergent (disagrees with opposite tests)

What is criterion-related validity?

Assesses whether the test is valid as measured against a ‘gold standard’.

• Concurrent (a current standard)

• Predictive (a future standard)

What is reliability?

Consistency/reproductivity

What does the correlation coefficient (r) show?

Relationship between two sets of scores

What does a correlation of +1 mean?

A correlation of +1 means perfect agreement and excellent reliability, and over .7 means very strong.

What is internal consistency and how do you measure it?

All items in a test are measuring the same thing. You can measure it with Cronbach’s alpha and split-half reliability.

What is test-retest reliability?

Performance stability across time

What are the research effects?

• Placebo effect

• Hawthorne effect (behaving differently bc being watched)

• John Henry effect (control group changing to “compete” w/ exper. group)

• Halo effect

• Pygmalion effect (researcher’s/observer’s expectations influence respondent)

Types of response bias?

• Acquiescence

• Social desirability

• Recall effects

• Sensitive information

• Respondents’ preferences