PS295 Lecture Notes - Lecture 8: Internal Validity, Experiment, Demand Characteristics
Document Summary
Internal validity: refers to study as a whole, is the causal conclusion supported by the study. External validity: the degree to which the results obtained in one study can be generalized to other samples, settings, and procedures, the generalizability of the research results to other settings. There may sometimes be trade-offs between internal and external validity: features that produce high internal validity may produce lower external validity, the experimenters dilemma , example: laboratory experiments. Common criticism of lab experiments: samples are not representative, not realistic (artificial and unnatural) Main goal is not to generalize specific results: internal validity is the more primary goal, goal is to test hypotheses about causes, if hypotheses are supported then they, not the particular results of the study, are generalized. Unrepresentative samples: lab findings are often replicated in other settings. Types of research designs and internal validity: quasi-experiments.
