Starting at the Beginning: An Introduction to Coefficient Alpha and Internal Consistency

Abstract

Cronbach's a 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 a from other indexes of internal consistency (split-half reliability and Kuder-Richardson 20) and discusses four myths associated with a: (a) that it is a fixed property of the scale, (b) that it measures only the internal consistency of the scale, (c) that higher values are always preferred over lower ones, and (d) that it is restricted to the range of 0 to 1. It provides some recommendations for acceptable values of a in different situations.

Relationships between young drivers’ personality characteristics, risk perceptions, and driving behaviour

“…Table 1 contains the means, standard deviations, Cronbach Alpha values and intercorrelations among the variables. At the generally accepted level (α ≥ .70), the internal consistency of all scales was acceptable (Steiner, 2003). Speeding was correlated with three of the risk perception variables (r = .25, p < .01 with Likelihood of Accident, r = .22, p < .01 with Efficacy, and r = -.49, p < .01 with Aversion to Risk Taking) and four of the personality variables (r = .32, p < .01 with Anger, r = .33, p < .01 with Excitement-Seeking, r = -.37, p < .01 with Altruism, and r = .34, p < .01 with Normlessness).…”

Driver trust in five driver assistance technologies following real-world use in four production vehicles

“…Cronbach's alpha was computed to assess whether the five statements reliably measured the same construct. A Cronbach's alpha value greater than or equal to 0.80 is considered adequate for research tools (Streiner 2003).…”

Professor-Student Rapport Scale: Psychometric properties of the brief version

“…This is evidence of acceptable internal consistency that is not so high as to suggest item redundancy (Streiner, 2003).…”