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. 2001 Nov 15;58(22):2173-81; quiz 2182-3. Affiliations
Review Establishing the internal and external validity of experimental studiesM K Slack et al. Am J Health Syst Pharm. 2001. AbstractThe information needed to determine the internal and external validity of an experimental study is discussed. Internal validity is the degree to which a study establishes the cause-and-effect relationship between the treatment and the observed outcome. Establishing the internal validity of a study is based on a logical process. For a research report, the logical framework is provided by the report's structure. The methods section describes what procedures were followed to minimize threats to internal validity, the results section reports the relevant data, and the discussion section assesses the influence of bias. Eight threats to internal validity have been defined: history, maturation, testing, instrumentation, regression, selection, experimental mortality, and an interaction of threats. A cognitive map may be used to guide investigators when addressing validity in a research report. The map is based on the premise that information in the report evolves from one section to the next to provide a complete logical description of each internal-validity problem. The map addresses experimental mortality, randomization, blinding, placebo effects, and adherence to the study protocol. Threats to internal validity may be a source of extraneous variance when the findings are not significant. External validity is addressed by delineating inclusion and exclusion criteria, describing subjects in terms of relevant variables, and assessing generalizability. By using a cognitive map, investigators reporting an experimental study can systematically address internal and external validity so that the effects of the treatment are accurately portrayed and generalization of the findings is appropriate. Similar articles
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What are internal and external threats to validity when an experimental research is conducted?Internal validity is the degree of confidence that the causal relationship you are testing is not influenced by other factors or variables. External validity is the extent to which your results can be generalized to other contexts. The validity of your experiment depends on your experimental design.
What are threats to internal validity of experimental studies?There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition.
What are four common threats to internal validity when conducting experimental research designs?History, maturation, selection, mortality and interaction of selection and the experimental variable are all threats to the internal validity of this design.
What are three major threats to the internal validity of experiments and possible solutions?Threats to Internal Validity. Attrition: Attrition is bad for your research because it leads to a bias. ... . Confounding variables: When your research has an extra variable related to the treatment you applied to your sample group that affects your results, then that leads to confusion. ... . Diffusion: This is a tricky one.. |
What are the internal and external threats to validity of experimental research?
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