Reference table
Internal, external and ecological validity compared
Three kinds of validity that pull in different directions
A side-by-side table of internal, external and ecological validity for researchers planning a study. Each row gives the question that kind of validity answers, what usually threatens it and how to raise it. Use it when choosing between a controlled session and a more realistic one, and to explain the trade-off to stakeholders. Koji's self-paced interviews on the participant's own device are one way to add realism without a field visit.
Where this appears
What's in this reference table
| Question it answers | Threatened by | How to raise it | |
|---|---|---|---|
| Internal validity | Did the thing we changed cause the effect we saw? | Distractions, uneven groups, other changes at the same time | Control the setting and hold everything else constant |
| External validity | Does the result hold for other people, places and times? | Narrow or convenient samples | Sample people who match the users you care about |
| Ecological validity | Do the study conditions look like real life? | Artificial settings, invented tasks, demo data, observers | Real settings, real goals, their own devices, fewer observers |
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<a href="https://www.koji.so/visuals/internal-external-ecological-validity-compared"><img src="https://www.koji.so/visuals/internal-external-ecological-validity-compared/internal-external-ecological-validity-compared.png" alt="Table comparing internal, external and ecological validity: the question each answers, what threatens it and how to raise it" width="1200" height="715" /></a>
<p>Source: <a href="https://www.koji.so/visuals/internal-external-ecological-validity-compared">Internal, external and ecological validity compared</a>, Koji</p>
