is_specified_input_of effect size estimate confidence interval calculation eta-squared Alejandra Gonzalez-Beltran Eta-squared is a biased estimator of the variance explained by the model in the population (it estimates only the effect size in the sample). Eta-squared describes the ratio of variance explained in the dependent variable by a predictor while controlling for other predictors, making it analogous to the r2. This estimate shares the weakness with r2 that each additional variable will automatically increase the value of η2. In addition, it measures the variance explained of the sample, not the population, meaning that it will always overestimate the effect size, although the bias grows smaller as the sample grows larger. Orlaith Burke Philippe Rocca-Serra http://en.wikipedia.org/wiki/Effect_size#Eta-squared.2C_.CE.B72 η2 estimate pending final vetting