Magnitude of effect (ME) statistics are an important alternative to statistical significance. Why methodologists encourage the use of ME indices as interpretation aids is explained, and different types of ME statistics are discussed. The basic concepts underlying effect size measures are reviewed, and how to compute them from published reports even when results are incompletely reported is explained. Effect size measures are increasingly important, especially since the American Psychological Association publication manual explicitly suggests that they be reported. (Contains 25 references.) (SLD)