Internal validity is the degree to which the results of an experiment or study accurately reflect the true relationship between the variables being studied. It is an important concept in the field of research methodology and is used to evaluate the quality of data in a study.
Definition
Internal validity is defined as the degree to which the results of a study accurately reflect the true relationship between the variables being studied. The validity of a study is determined by the degree to which the results can be applied to the population being studied. This is achieved by controlling for external factors, such as the influence of other variables, that could potentially affect the results of the study.
History
The concept of internal validity was developed in the 1950s by the psychologist Donald Campbell. Campbell proposed that internal validity is achieved when the results of a study are not influenced by any other factors besides the variables being studied. This was a revolutionary concept at the time, as it challenged the traditional notion of cause-and-effect relationships in research.
Characteristics
Internal validity is an important concept in experimental research, as it ensures that the results of a study are not affected by any external factors. To ensure internal validity, researchers must control for any potential confounding variables, such as the influence of other variables, that could potentially affect the results of the study. Additionally, researchers must also ensure that the sample size is large enough for the results to be representative of the population being studied.
References
Campbell, D.T. (1957). Factors relevant to the validity of experiments in social settings. Psychological Bulletin, 54(3), 297-312.
Cook, T.D., & Campbell, D.T. (1979). Quasi-Experimentation: Design & Analysis Issues for Field Settings. Chicago, IL: Rand McNally.
Shadish, W.R., Cook, T.D., & Campbell, D.T. (2002). Experimental and Quasi-Experimental Designs for Generalized Causal Inference. Boston, MA: Houghton Mifflin.