The world should not revolve around Cronbach’s alpha ≥ .70
DOI:
https://doi.org/10.20882/adicciones.1576Keywords:
Cronbach's alpha, Reliability, Cut point, Methodology.Abstract
In the field of addiction measurement it is common to use the alpha (α) coefficient as an estimator of the internal consistency of a measurement instrument. However, is the cut-off point α ≥ .70 always an acceptable value? This question is addressed in this letter. To support the ideas presented, data were simulated in the R program, where the alpha coefficient was examined under different conditions. The results obtained are important because they allow rethinking the methodological practice of alpha in the context of addictions, because a single value (α ≥ 0.70) is not enough to guarantee the reliability of the scores of a measurement instrument, being necessary to examine and report the inter-item correlation matrix, its average, its standard deviation, the number of items, the review of previous or meta-analytical studies. This in order to assess the reliability from a data set and not only through a single value, and declare: "acceptable" or "not acceptable". Understanding that in measurement it is necessary to look at the forest and not just the tree.References
Benito, A., Calvo, G., Real-López, M., Gallego, M. J., Francés, S., Turbi, Á. y Haro, G. (2019). Creación y estudio de las propiedades psicométricas del cuestionario de socialización parental TXP. Adicciones, 31, 117-135. doi:10.20882/adicciones.983.
Cho, E. y Kim, S. (2015). Cronbach’s coefficient alpha. Organizational Research Methods, 18, 207-230. doi:10.1177/1094428114555994.
Cicchetti, D. V. (1994). Guidelines, criteria, and rules of thumb for evaluating normed and standardized assessment instruments in psychology. Psychological Assessment, 6, 284-290. doi:10.1037/1040-3590.6.4.284.
Cortina, J. M. (1993). What is coefficient alpha? An examination of theory and applications. Journal of Applied Psychology, 78, 98-104. doi:10.1037/0021-9010.78.1.98.
Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16, 297-334. doi:10.1007/BF02310555.
Lance, C. E., Butts, M. M. y Michels, L. C. (2006). The sources of four commonly reported cutoff criteria. Organizational Research Methods, 9, 202-220. doi:10.1177/1094428105284919.
Murphy, K. R. y Davidshofer, C. O. (2004). Psychological Testing: Principles and Applications (6th ed.). New Jersey, USA: Pearson/Prentice Hall.
Nunnally, J. (1978). Psychometric theory (2nd ed.). New York: McGraw-Hill.
Peters, G. J. Y. (2014). The alpha and the omega of scale reliability and validity: Why and how to abandon Cronbach’s alpha and the route towards more comprehensive assessment of scale quality. The European Health Psychologist, 16, 56-69.
Peterson, R. A. (1994). A meta-analysis of Cronbach’s coefficient alpha. Journal of Consumer Research, 21, 381. doi:10.1086/209405.
Raykov, T. y Marcoulides, G. A. (2019). Thanks coefficient alpha, we still need you! Educational and Psychological Measurement, 79, 200-210. doi:10.1177/0013164417725127.
Ventura-León, J. L. (2019). Is this the end for Cronbach’s alpha? Adicciones, 31, 80-81. doi:10.20882/adicciones.1037.
