Research Methodology
External Validity
The extent to which the results of a study can be generalized to and across other situations, people, stimuli, and times.
What is External Validity?
External validity assesses whether the causal relationships found in a highly controlled study apply outside of that specific context. It relies heavily on how representative the sample is and how realistic the experimental setting is.
Why External Validity Matters
Research is mostly useless if its findings only apply to the narrow, artificial conditions of a laboratory or to a weirdly specific sample.
Example
A study finds that a memory technique works flawlessly on university psychology undergraduates in a lab, but the researcher must test if it works for elderly adults in their homes to establish external validity.
Common Mistakes
- Assuming external validity automatically follows from a large sample size.
- Sacrificing external validity too much in the pursuit of perfect internal validity.