Robert Marzano Research Laboratory

Advance organizers provide students with an opportunity to preview content prior to the presentation of the actual content in class.

The following table presents a summary of findings from two meta-analyses of the experimental/control action research studies in Marzano Research Laboratory’s Meta-Analysis Database which utilized this strategy (for a listing of the action research studies, click here). One meta-analysis was conducted using the reported effect sizes from the action research studies in our database. The second meta-analysis (findings reported in parentheses) was conducted using effect sizes that were corrected for attenuation due to a lack of reliability often associated with teacher-designed assessments of student academic achievement (for a discussion of attenuation and meta-analysis and the method used to correct for attenuation click here). Both meta-analyses employed a random-effects model of error (for a discussion of models of error in meta-analysis click here).

Consulting a table of the normal curve, the overall percentile gain associated with the corrected weighted average effect size of 0.01 is 0.0040. This suggests that on the average, the use of advance organizers by teachers in the action research studies represent no difference over what was expected when they did not use advance organizers.

The effect sizes reported in the table are weighted averages of all the effect sizes from the action research studies and should be considered estimates of the true effect size of the experimental condition (i.e., use of advance organizers). For example, consider the corrected weighted average effect size reported in parentheses, 0.01 ± 0.23. This mathematical expression represents the 95% confidence interval and includes the range of effect sizes (-0.22 to 0.24) in which one can be 95% certain the true effect size falls. When the confidence interval does not include 0.00, the weighted average effect size can be considered statistically significant. In other words, an effect size of 0.00 would not be considered a reasonable assumption.

It is worth noting that these findings are consistent with the weighted average effect sizes previously reported for a meta-analysis of seven action research studies (Effect Size = -0.01 ± 0.22, Corrected Effect Size = -0.01 ± 0.25). When those findings were combined with 14 additional action research studies, the corrected weighted average effect size increased slightly to 0.01. However, these findings are not consistent with earlier meta-analytic studies on advance organizers. In light of the other research, it is likely that the weighted average effect size would change with additional action research studies.