Being Inconsistent About Consistency: When Coefficient Alpha Does and Doesn't Matter
Top Cited Papers
- 10 June 2003
- journal article
- Published by Taylor & Francis in Journal of Personality Assessment
- Vol. 80 (3) , 217-222
- https://doi.org/10.1207/s15327752jpa8003_01
Abstract
One of the central tenets of classical test theory is that scales should have a high degree of internal consistency, as evidenced by Cronbach's α, the mean interitem correlation, and a strong first component. However, there are many instances in which this rule does not apply. Following Bollen and Lennox (1991), I differentiate between questionnaires such as anxiety or depression inventories, which are composed of items that are manifestations of an underlying hypothetical construct (i.e., where the items are called effect indicators) and those such as Scale 6 of the Minnesota Multiphasic Personality Inventory (Hathaway & McKinley, 1943) and ones used to tap quality of life or activities of daily living in which the items or subscales themselves define the construct (these items are called causal indicators). Questionnaires of the first sort, which are referred to as scales in this article, meet the criteria of classical test theory, whereas the second type, which are called indexes here, do not. I discus...Keywords
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