SPSS FAQ What does Cronbachs alpha mean?
Cronbach’s alpha is a measure of internal consistency, that is, how closely related a set of items are as a group. A “high” value of alpha is often used (along with substantive arguments and possibly other statistical measures) as evidence that the items measure an underlying (or latent) construct. However, a high alpha does not imply that the measure is unidimensional. If, in addition to measuring internal consistency, you wish to provide evidence that the scale in question is unidimensional, additional analyses can be performed. Exploratory factor analysis is one method of checking dimensionality. Technically speaking, Cronbach’s alpha is not a statistical test – it is a coefficient of reliability (or consistency). Cronbach’s alpha can be written as a function of the number of test items and the average inter-correlation among the items. Below, for conceptual purposes, we show the formula for the standardized Cronbach’s alpha: Here N is equal to the number of items, c-bar is the aver
