Starting at the beginning: An introduction to coefficient alpha and internal consistency

Cronbach's α is the most widely used index of the reliability of a scale. However, its use and interpretation can be subject to a number of errors. This article discusses the historical development of α from other indexes of internal consistency (split-half reliability and Kuder-Richardson 20) and discusses four myths associated with α: (a) that it is a fixed property of the scale, (b) that it measures only the internal consistency of the …