Reliability and Validity Flashcards
What is reliability
Reliability refers to the consistency/repeatability of results of a measurement. “How” reliable something is relative and depends on the situation.
Types of reliability
- Observers: Inter-Observer reliability
- Observations: Internal (Split-half) reliability
- Occasions: Test-retest reliability
What is inter-observer reliability?
Inter-observer reliability is the degree to which observers agree upon an observation or judgement
• Can be frequency or categorical judgement
How is inter-observer reliability tested?
Measure by looking at shared relationships between observers (i.e. correlation). Cohen’s kappa, Pearson’s correlation coefficient (r), etc. depending on whether continuous or discrete
What is internal reliability?
Internal reliability is the degree to which specific items/observations in a multiple item measure behave the same way. I.e. are they measuring the same thing?
How is internal reliability tested?
Tested by dividing test into 2 halves, then looking at correlation between them. If it has high internal reliability, an individual’s performance on the first half should correlated with the second half.
What is test-retest reliability?
Test-retest reliability is the extent to which scores on a test/measure remain stable over time.
What is validity?
Validity refers to how well a measure or an
operationalised variable corresponds to what it is supposed to measure/represent.
Types of validity
- Internal validity
- External validity
- Population validity
- Ecological validity
- Construct validity
- Content validity
- Criterion validity
Internal validity
• How convincing is the evidence for causality in a study/series of experiments?
• i.e. how strong is the inference that the independent
variable and the dependent variable are causally
related?
J.S. Mill: 3 requirements to establish causality
- Covariation
- Temporal Sequence
- Eliminating confounds (rival explanations/hypotheses)
- Third-variable problem
Equifinality
Another threat to internal validity. Most things have multiple causes .
External validity
How well does a causal relationship hold across different people, settings, treatment variables, measurements and time. Two types: Ecological and population validity.
Population validity
- Making cross-cultural inferences from Western, Educated, Industrialized, Rich, Democratic samples?
- Differences in tasks ranging from motivation, reasoning and even visual perception
- Muller-Lyer Illusion: Americans vs. the San people of the Kalahari
Ecological Validity
How well do results of laboratory experiments generalise to real-life settings?
• E.g. aggression studies in the lab vs. in real life
• Bandura (1961, 1963): Bobo doll experiment