Lecture video for “Data Sense: An Introduction to Statistics for the Behavioral Sciences” by Barton Poulson. This video covers Chapter 10: The Analysis of Variance (ANOVA), Section 07: Effect Size. It explains how eta-squared, which is calculated from the sum of squares, can be used to describe the size of a statistical effect in ANOVA. The book and complete set of videos may be purchased at http://kendallhunt.com/poulson/.