Goal of Psychology: to determine the Underlying “laws” of behavior. External Validity Goal of Psychology: to determine the Underlying “laws” of behavior. External Validity – the extent to which the results of an experiment can be applied to and across different persons, settings, and times. (ie14)

Population Validity – ability to generalize results from the sample to a larger population. Random Selection – from a population should insure generalization to the experimentally accessible population. (ie14)

Target Population - larger population to which results are generalized. (ie14)

ALL PERSONS WITH DEPRESSION Persons Diagnosed Willing Control Studied (ie14)

Ecological Validity: extent to which results can be generalized across settings or environmental conditions. (ie14)

Temporal Validity – generalizability across time. Seasonal Variation Cyclical Variation Personological Variation e.g., are you planning a mid-life crisis? (ie14)

Treatment Variation Validity - Degree the results of a study can be generalized across variations in the treatment Outcome validity - Degree to which the results of a study generalize across related dependant variables. (ie14)

Relationship between Internal & External Validity To obtain high Internal Validity we often create very artificial study settings. To establish external validity we often need to determine if the finding applies across setting, locations, cultures etc. (ie14)