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Moral de la Rubia, J. (2023). Two measures of skewness based on mode: calculation and interpretative rules. Psychologia, 17(2), 39–54. https://doi.org/10.21500/19002386.6542 (Original work published June 1, 2023)
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Abstract

This article presents in exemplified form two measures of skewness. Although they may be useful when the distribution is unimodal, they are not reported in psychological research. One is Pearson’s standardized distance from the mean to the mode. The other is the Bickel’s robust measure of skewness. It is shown how to compute the point and interval estimate with the R program. Moreover, interval confidences at 90%, 95% and 99% are calculated with 10 000 draws with replacement from normally distributed samples-population with different sizes to have interpretative guidelines for symmetry. It is concluded that the ∓0.1 rule does not apply with these measures, Grenander’s mode provides the most efficient confidence intervals, but Bickel’s skewness is the option with ordinal variables.

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