Review and “Vote Count” Analysis of OTL-Effect Studies

In the fourth chapter an overview is given of 51 primary studies, conducted during the last twenty years. Schematic summary descriptions are put together in a large summary table. Although quantitative meta-analysis of these studies was beyond the scope of this review study, some basic summary tables were produced to provide an overall orientation on how OTL had been researched and what can be concluded about its effectiveness. It is concluded that the vote count measure of OTL, (i.e. the percentage of effect sizes that were statistically significant and positive) established in this study, and which was 44 %, is of comparable size to other effectiveness enhancing conditions like achievement orientation, learning time and parental involvement, but dramatically higher than vote count measures for variables like cooperation and educational leadership. What should be considered is that vote counting is a rather crude procedure and that comparison of quantitative effect sizes is more informative.