Advancing Alpha: Measuring Reliability With Confidence

In this research, we present the inferential statistics for Cronbach's coefficient alpha. This index of reliability is extremely important in consumer research. The estimation of alpha and its confidence intervals are described and an analytical demonstration illustrates the effects on these statistics of their components, including the number of items, the item intercorrelations, and sample size. SAS and SPSS programs are offered for easy implementation. We conclude with a prescription that every time a researcher reports a coefficient alpha, the confidence interval for alpha should accompany the alpha estimate.