Cronbach's alpha in mathematics education research: Its appropriateness, overuse, and alternatives in estimating scale reliability

Critiques of coefficient alpha as an estimate of scale reliability are widespread in the literature. However, the continuous overuse of this statistic in mathematics education research suggests a disconnection between theory and practice. As such, this article argues, in a non-technical way, for the limited usefulness of coefficient alpha, its overuse, and its alternatives in estimating scale reliability. Coefficient alpha gives information only about the degree of the interrelatedness of a set of items that measures a construct. Contrary to the widely circulated misconceptions in mathematics education research, a high coefficient alpha value does not mean the instrument is reliable, and it does not imply the instrument measures a single construct. Coefficient alpha can only be dependable as an estimate of reliability under verifiable and restrictive conditions. I expose these conditions and present steps for their verification in empirical studies. I discuss some alternatives to coefficient alpha with references to non-technical articles where worked examples and programming codes are available. I hope this exposition will influence the practices of mathematics education researchers regarding estimation of scale reliability.