Limitations of coefficient alpha as an index of test unidimensionality1

Samuel B. Green, Robert W. Lissitz, Stanlen A. Mulaik

Research output: Contribution to journalArticlepeer-review

333 Scopus citations


Confusion in the literature between the concepts of internal consistency and homogeneity has led to a misuse of coefficient alpha as an index of item homogeneity. Coefficient alpha is actually a complexly determined test statistic, item homogeneity only being one influence on its magnitude. The related statistic, the average intercorrelation, has similar difficulties. Several indices of item homogeneity derived from the model of common factor analysis are offered as alternatives.

Original languageEnglish (US)
Pages (from-to)827-838
Number of pages12
JournalEducational and Psychological Measurement
Issue number4
StatePublished - Dec 1977

ASJC Scopus subject areas

  • Education
  • Developmental and Educational Psychology
  • Applied Psychology
  • Applied Mathematics


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