Arab Educational Information Network

The aim of the current research is to get acquainted with the reality of using the “T” test and the one-way ANOVA test as inferential parametric statistical tests considering the concepts of test power and the effect size of according to the sample size. The sample of research published in the journal of psychological and educational research issued by the Bahrain University in the period from 2008 to 2018, in which the “T” test and the one-way ANOVA were used, which reached 94 research. The research concluded in some of its results that the power of the statistical test increases with the increase of the sample size, while the effect size does not differ according to the sample size, and that the effect sizes were weak and very weak, and the rate of the first type error in this research was approximately 21.4%, while the rate of the second type error contained approximately 21.7%. (Published abstract)