The problem with Cronbach's Alpha: comment on Sijtsma and van der Ark (2015).

Knowledge of a scale's dimensionality is an essential preliminary step to the application of any measure of reliability derived from classical test theory--an approach commonly used is nursing research. The focus of this article is on the applied aspects of reliability and dimensionality testing. Throughout the article, the Self-Care of Heart Failure Index is used to exemplify real-world data challenges of quantifying reliability and to provide insight into how to overcome such challenges.