Reliability & Validity, Lecture notes of Research Methodology

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Reliability & Validity

Reliability & Validity • Roughly speaking, validity is the

accuracy ,

or “truth”, of information and reliability isthe^ consistency^ of information.

Reliability and Validity (cont’d) Question: Is it possible to have a measure thatis valid but not reliable?

Reliability: Different Types • Test-retest reliability • Internal consistency reliability – Split-half – Cronbach alpha • Interrater reliability

Construct Validity

-^ Adequacy of the operational definition of the variable. •^ Four types:^ 1. Face^ 2. Convergent^ 3. Divergent^ 4. Criterion

Construct Validity Do You Like Crunchy Peanut Butter?^ OR The Miracle of Low Face Validity

-^ Face validity - Does the measure

appear^ to measure what it is supposed to?

Construct Validity

Criterion - Predicts behavior designed to predict.^ SAT^

College GPA Risk Assessment Scale^

Alcohol Relapse

Internal & External Validity • Internal - Ability to draw conclusions about causalrelationships from data. • External – Extent to which the results can begeneralized to other populations & settings. • From Chapter 4, what are the two techniques ofthe experimental method? – Experimental Control – Randomization – What type of validity do these address?

Reactivity

-^ Awareness of being measured can change anindividual’s behavior.^ – E.g. – Imagine that you realize that a researcher ismeasuring your propensity to litter. Would you behavethe same as if you weren’t being observed? •^ What is the relation between reactivity and^ A) construct validity?^ B) internal validity?^ C) external validity?