A Comprehensive Review of Effect Size Reporting and Interpreting Practices in Academic Journals in Education and Psychology

Null hypothesis significance testing has dominated quantitative research in education and psychology However the statistical significance of a test as indicated by a p value does not speak to the practical significance of the study Thus reporting effect size to supplement p value is highly recommended by scholars Journal editors and academic associations As a measure of practical significance effect size quantifies the size of mean differences or strength of associations and directly answers the research questions Furthermore a comparison of effect sizes across studies facilitates meta analytic assessment of the effect size and accumulation of knowledge In the current comprehensive review we investigated the most recent effect size reporting and interpreting practices in 1 243 articles published in 14 academic journals from 2005 to 2007 Overall 49% of the articles reported effect size-57% of which interpreted effect size As an empirical study for the sake of good research methodology in education and psychology in the present study we provide an illustrative example of reporting and interpreting effect size in a published study Furthermore a 7 step guideline for quantitative researchers is also summarized along with some recommended resources on how to understand and Interpret effect size