Ventajas del alfa ordinal respecto al alfa de Cronbach ilustradas con la encuesta AUDIT-OMS

Objectives. Demonstrate the advantages of using ordinal alpha when the assumptions for Cronbach's alpha are not met; show the usefulness of ordinal alpha with the Chilean version of the WHO Alcohol Use Disorders Identification Test (AUDIT); and provide the commands in R programming language for performing the respective calculations. Methods. Cronbach's alpha and ordinal alpha were compared in an AUDIT questionnaire administered to 419 students at a Chilean university. Results. In all domains, the result using ordinal alpha was greater than with Cronbach's alpha. This finding was consistent with the literature on the subject. When ordinal alpha was chosen, the reliability of each domain and the survey as a whole was accepted, which does not always happen with Cronbach's alpha. Conclusions. In making decisions about the reliability of a dimension, consideration should be given to an index that meets the required assumptions for using it in order to avoid erroneous conclusions that can have an appreciable effect on research. The values of Cronbach's alpha underestimate the reliability of an instrument when working with ordinal scales.