A Coefficient Alpha for Test-Retest Data

Samuel B. Green

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Transient errors are caused by variations in feelings, moods, and mental states over time. If these errors are present, coefficient alpha is an inflated estimate of reliability. A true-score model is presented that incorporates transient errors for test-retest data, and a reliability estimate is derived. This estimate, referred to as the test-retest alpha, is less than coefficient alpha if transient error is present and is less susceptible to effects due to item recall than a test-retest correlation. An assumption underlying the test-retest alpha is essential tau equivalency of items. A test-retest split-half coefficient is presented as an alternative to the test-retest alpha when this assumption is violated. The test-retest alpha is the mean of all possible test-retest split-half coefficients.

Original languageEnglish (US)
Pages (from-to)88-101
Number of pages14
JournalPsychological Methods
Issue number1
StatePublished - Mar 2003

ASJC Scopus subject areas

  • Psychology (miscellaneous)


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