Reliability: The degree to which a measurement can be successfully repeated.

Types of Reliability Inter-rater reliability Test-retest Alternate-form Split-half Internal consistency

Inter-rater reliability Degree of agreement among observers Highest when behavior being observed is simple and obvious Rating of participant boredom vs. Rating of # of participant yawns

Test-retest reliability Same test is given to participants multiple times Advantages: –Uses same test items –Simple to do Disadvantages: –

Alternate-form A second test with similar items is administered Advantages: –Less repeat-item contamination –Little time passes (unstable constructs less likely to change) Disadvantage: –

Split-half Test is split in half (often even vs. odd questions), and halves are compared Advantages: –Less repeat-item contamination –No time passes (unstable constructs less likely to change) Disadvantage: –Different items used in each half –Requires a longer test

Internal consistency Mean of all split-half reliabilities Known as Cronbach’s alpha Does not assess unidimensionality

Validity: The degree to which something (a measuring device, a concept) corresponds to a standard.

Types of Validity Face validity Content validity Criterion-related validity –Predictive (future) –Concurrent (present) Construct validity –Convergent validity –Discriminant validity

Challenges with Constructs: Labels Attitude = evaluative component Attitude = f(cognitions, behavior) Attitude = belief = opinion = value Attitude = answers on Likert attitude questions ???

Bias: Systematic differences in a measure despite equivalence on the latent construct.

Depression Index How much to you agree with the following statements: 1) I would rather stay home than go to a party. 2) …