Definition: The extent to which repeated measurements lead to the same results. In psychometrics, reliability refers to the extent to which respondents have similar scores when they take a questionnaire on multiple occasions. Noteworthy, reliability does not imply validity. Furthermore, additional types of reliability besides internal consistency exist, including: test-retest reliability, parallel forms reliability and interrater reliability.

Related terms: Consistency, Internal consistency, Quality Criteria, <a href='/glossary/replicability/'>Replicability</a>, <a href='/glossary/reproducibility/'>Reproducibility</a>, <a href='/glossary/validity/'>Validity</a>

References: Bollen (1989), & Drost (2011)

Drafted and Reviewed by: Annalise A. LaPlume, Mahmoud Elsherif, Eduardo Garcia-Garzon, Kai Krautter, Olmo van den Akker

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