1. Credits p. 0_2 2. Table of contents p. 1 3. Note from Executive Director Felice J Levine p. 3 4. Editors' Note Drew Gitomer, Laura Goe. p. 4 5. Strategies for Improving Precision in Group-Randomized Experiments Stephen W Raudenbush, Andres Martinez, Jessaca Spybrook. p. 5 6. Using Covariates to Improve Precision for Studies That Randomize Schools to Evaluate Educational Interventions Howard S Bloom, Lashawn Richburg-Hayes, Alison Rebeck Black. p. 30 7. Intraclass Correlation Values for Planning Group-Randomized Trials in Education Larry V Hedges, E C Hedberg p. 60 8. Erratum p. 88