Emphasis on effect sizes is a rapidly rising tide as over 20 journals in various fields of research now require that authors of research reports provide estimates of effect size. For certain kinds of applied research it is no longer considered acceptable only to report that results were statistically significant. Statistically significant results indicate that a researcher has discovered evidence of a real difference between parameters or a real association between variables, but it is one of unknown size. Especially in applied research such statements often need to be supplemented with estimates of how different the average results for studied groups are or how strong the association between variables.
