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INTERNATIONAL JOURNAL OF STATISTICS IN MEDICAL RESEARCH, vol.11, pp.88-96, 2022 (Scopus)
In the field of health and other sciences, effect size (ES) provides a scientific approach to the effectiveness of
treatment or intervention. The p-value indicates whether the statistical difference depends on chance, while ES gives
information about the effectiveness of the treatment or intervention, even if the difference is not significant. For this
reason, ES has become a very popular measure in recent years. It depends on which ES will be used based on the
distribution of data and the number of groups. In this study, parametric and non-parametric ES were evaluated for two
independent groups.
When the literature was examined, there were no studies aimed at evaluating the reference values of the parametric and
non-parametric ES methods used for two independent groups. In this study, the reference values of parametric and
non-parametric ES methods for two independent groups were re-evaluated by a simulation study. As a result, the very
small reference value of parametric ES methods was determined differently from the literature. It has been seen that the
reference values of non-parametric ES methods are valid in cases where the skewness is low, and new reference values
have been proposed at the varying skewness level