Observer Drift
Definition
A gradual, unintended change in how an observer applies a definition over time, so later data are scored by different standards than earlier data. It is a threat to accuracy that neither observer notices, and it is caught by periodic agreement checks and by retraining against the written definition.
In plain language
Over time, an observer slowly starts to score the behavior in a new way. They do not notice it. Regular checks catch it.
Example
After weeks of recording, a technician starts counting brief taps as hits, which the definition never included.
Not observer drift
A learner behaving differently because they know they are being watched. That change is reactivity, in the learner rather than the observer.
See also
Written from
- johnston-pennypacker-2020
- kazdin-1979
Written from Johnston, Pennypacker and Green (2020) and Kazdin (1979). No textbook glossary consulted.
This entry has not yet been through clinical review. Treat it as a draft.