Chapter 8: Construct and External Validity in Experimental Research This multimedia product and its contents are protected under copyright law. The following are prohibited by law: Any public performance or display, including transmission of any image over a network; Preparation of any derivative work, including the extraction, in whole or in part, of any images; Any rental, lease, or lending of the program

Construct Validity Definition—extent to which we can infer higher-order constructs for our operations Constructs are used for Research participants Independent variable Dependent variable Experimental setting

How to Assess Construct Validity Have a clear definition of the construct of interest Problem is identifying prototypical features of the constructs Affects ability to identify the concrete operations used to represent the construct

Assess the match between the constructs and the operations used to represent them Ways to assess Content validity Criterion-related validity Predictive concurrent

Threats to Construct Validity Inadequate explanation of the construct Construct confounding Mono-operation bias Confounding constructs with level of constructs Reactive self-report changes Reactivity to the experimental situation Experimenter effects

Novelty and disruption effects Compensatory equalization Compensatory rivalry Resentful demoralization Treatment diffusion

Reactivity to the Experimental Situation Refers to research participants motives and perceptions influencing their response to the DV Motive and perceptions influenced by the demand characteristics of the experiment Primary motive--positive Self-presentation Condition producing positive self-presentation motive Implication for research Intertreatment interaction Intratreatment interaction

Ways experimenter may bias the study Experimenter Effect Experimenter’s motive of supporting the study hypothesis can lead to bias Ways experimenter may bias the study Experimenter attributes Experimenter expectancies Effect on experimenter—recording bias Effect on research participant-- Magnitude of expectancies—can exist in animal and human research and can be greater than the IV

External Validity Definition—generalizing across people, settings, treatment variations, outcomes and times Represents a test of interactions

Threats to External Validity Population validity Target population Experimentally accessible population Requires generalization from sample to target population Ecological validity Temporal validity Seasonal variation Cyclical variation Treatment variation validity Outcome validity

External Validity Concerns Cautions in evaluating external validity Some studies conducted to increase knowledge and not to generalize to a real life situation Some studies assess a theoretical process Moving out of the laboratory does not insure generalization Relationship between internal and external validity—often an inverse relationship