Test-Retest Reliability
Test-Retest reliability reflects the variation in measurements taken by an instrument on the same subject under the same conditions1. In other words, Test-Retest reliability quantifies the similarity of scores when a study participant completes a test at 2 separate instances2.
- It is generally indicative of reliability in situations when raters are not involved or rater effect is neglectable, such as self-report survey instrument1.
Interpretation
If this test was reliable, we would expect the 2 scores to be similar, if not identical, on both occasions (assuming that the person has not changed in the interim)2.
Duration Between Tests
- When assessing test-retest reliability, the length of time between time 1 and 2 creates an issue since there is a fine balance the researchers must find with time since there is trade-off between 2 competing requirements2.
- The usual testretest interval is about 2 weeks, but this can be altered based on a number of factors2.
- The Longer the scale the less time is required between measurements (the person is less likely to remember all of their answers)2.
- Duration is also determined by how quickly the attribute being tested can change2.
References
1.
Koo TK, Li MY. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. Journal of Chiropractic Medicine. 2016;15(2):155-163. doi:10.1016/j.jcm.2016.02.012
2.
Streiner DL. Statistics Commentary Series: Commentary #15-Reliability. Journal of Clinical Psychopharmacology. 2016;36(4):305-307. doi:10.1097/JCP.0000000000000517
Citation
For attribution, please cite this work as:
Yomogida N, Kerstein C. Test-Retest
Reliability. https://yomokerst.com/The
Archive/Evidene Based
Practice/Reliability/test-retest_reliability.html