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Target validity: Bringing treatment of external validity in line with internal validity
Catherine R Lesko1, Benjamin Ackerman2, Michael Webster-Clark3
1Department of Epidemiology, Johns Hopkins School of Public Health, Baltimore, MD.
Current Epidemiology Reports
|February 15, 2021
Summary
This review addresses target bias, the gap between study findings and real-world application. It explores methods to enhance external validity, improving policy relevance by bridging this gap.
Area of Science:
- Epidemiology
- Biostatistics
- Health Services Research
Background:
- Target bias quantifies the discrepancy between study estimates and causal effects in the target population.
- It is a composite of internal and external bias, with internal validity extensively studied.
- This review focuses on enhancing external validity, a critical aspect for real-world applicability.
Purpose of the Study:
- To review threats to external validity in research studies.
- To present methods for improving the external validity of study findings.
- To enhance the policy relevance of research by addressing target bias.
Main Methods:
- Review of existing literature on threats to external validity.
- Exploration of methods to mitigate external bias, including outcome and sample membership modeling.
- Discussion of doubly robust methods when target population data is accessible.
Main Results:
- External bias stems from differences in effect modifier distributions between study samples and target populations.
- Methods exist to address external bias, contingent on the availability of target population data.
- Combining internal and external validity strategies strengthens policy relevance.
Conclusions:
- The policy relevance of research hinges on the studied interventions and the evaluated sample.
- Addressing both internal and external validity is crucial for maximizing the impact of study results.
- Improved external validity leads to more applicable and impactful policy decisions.
Keywords:
External ValidityGeneralizabilityInternal ValidityRandomized TrialsTarget PopulationTransportabilityMore Related Videos
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