Population
Generalization Across Subjects--The extent to which we can generalize from the experimental sample to the accessible population.
Interaction of Personological Variables and Treatment Effects--The extent to which the intervention differentially affects experimental participants based on their characteristics.
Ecological
Verification of the Independent Variable--The extent to which we can reproduce the exact implementation of the independent variable.
Multiple Treatment Interference--The extent to which we can generalize the effects of a single independent variable when participants are exposed to several independent variables.
Hawthorne Effect--The extent to which the extra attention provided to the participants during the study limits generalization to situations where the extra attention is not present.
Novelty and Disruption Effects--The extent to which the novelty or disruptive aspects of an independent variable limit generalization to situations where these novelty or disruptive aspects are not present or fade away.
Experimenter Effects--The extent to which the study's results are limited to the individual(s) implementing the independent variable.
Pretest Sensitization--The extent to which the study's results are limited to situations where only a pretest is utilized.
Posttest Sensitization--The extent to which the study's results are limited to situations where only a posttest is utilized.
Interaction of Time of Measurement and Treatment Effects--The extent to which the effects of the independent variable on the dependent variable will maintain through time.
Measurement of the Dependent Variable--The extent to which the generalizability of the study's results are limited to the particular dependent measure used.
Interaction of History and Treatment Effects--The extent to which the study's results can be generalized to a future time period.