The following table provides a quick reference to percentile gains or losses associated with specific effect sizes. To illustrate how to use this table, assume that a research study found that the use of a specific strategy produced an effect size of .20. You should first locate .20 in the column labeled [Effect Size.] In this case, it can be found in the first column. To the immediate right of this number is the percentile gain associated with the effect size. In this case, it is 8. This means that the score of the average person in the group that used the instructional strategy would be 8 percentile points higher than the score of the average person in the group that did not use the instructional strategy.