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Orlando, Fla.
October 31 - November 2, 2014
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2014 ASCD Conference on Educational Leadership

2014 ASCD Conference on Educational Leadership

October 31–November 2, 2014, Orlando, Fla.

Learn the secrets to great leadership practices, and get immediate and practical solutions that address your needs.



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What Works in Schools

by Robert J. Marzano

Table of Contents

Technical Notes

The following notes are intended to explain some of the more technical aspects of the research findings discussed in this book. These notes, however, are brief treatments of the topics addressed. For more detailed discussion, consult standard statistics textbooks, such as Cohen (1988); Cohen and Cohen (1975); Glass, McGaw, and Smith (1981); Glass, Willson, and Gottman (1975); and Hunter and Schmidt (1990).

Technical Note 1

One of the most common indices found in the research literature is the percent of variance explained (or PV). A basic assumption underlying the use of this index is that the percentage of variance explained by a predictor (or independent) variable (e.g., schooling) relative to a predicted (or dependent) variable (e.g., student achievement) represents the strength of relation between the two. Most commonly, a “set” of predictor variables is used.


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