What distinguishes external reliability from internal reliability?

External reliability is characterized by its focus on the consistency of research results across different contexts, times, or situations. This means assessing whether a study's findings can be reproduced when the research is repeated under varying conditions. For example, if a psychological test yields similar results over time or when administered by different researchers, it demonstrates strong external reliability. This aspect is essential for generalizing findings beyond the original study context to broader populations or varying circumstances.

In contrast, internal reliability pertains to the consistency within a single study, specifically how well the items or components of a measurement tool correlate with each other. This is often evaluated through statistical measures such as Cronbach's alpha, assessing whether all parts of a test effectively measure the same construct.

Understanding this distinction is crucial for researchers as it influences the interpretations and applications of their findings. External reliability enhances the credibility and applicability of results, making them relevant in real-world scenarios.