Test-retest reliability refers to what?

• A. The ability to produce consistent results across raters
• B. The ability to produce consistent results when tested at two different times
• C. The internal consistency of items within a scale
• D. The sensitivity to detect changes over time

Answer: (B)

Test-retest reliability measures the stability of a measure over time. When you administer the same test to the same people on two occasions under similar conditions, high similarity in scores indicates the instrument produces consistent results across time. This stability is typically assessed by correlating the two sets of scores (or using an intraclass correlation).

The correct idea is about consistency across two time points. The other options describe different concepts: consistency across raters is inter-rater reliability; internal consistency looks at how well items on a scale relate to each other; being sensitive to detect changes over time refers to responsiveness or change over time, not reliability.