Research Methodology
Reliability
The overall consistency of a measure.
What is Reliability?
Reliability is the degree to which an assessment tool produces stable and consistent results. If the same measurement is repeated under identical conditions, a reliable instrument will yield the same outcome.
Why Reliability Matters
It is a necessary (though not sufficient) condition for validity. Without reliability, random error swamps the signal, making it impossible to detect true relationships.
Example
A blood pressure monitor that gives the same reading when applied to the same patient three times in a row within two minutes is highly reliable.
Common Mistakes
- Assuming high reliability means the measurement is accurate or valid.
- Ignoring that reliability can degrade over time or across different administrators.