Online class Tuesday, March 30, 14h30-17h00

[Slides 278-342] A final note on one-way ANOVA models. Some general principles of experimental design: randomization, repetitions and pseudo-repetitions, additional predictors as ways of controlling unexplained variance (blocks in an ANOVA context). Two-way factorial designs: definition, notation. A first model (without interaction effects): the model equation and restrictions; additional assumptions. The two tests of interest and the  corresponding statistics with F distribution. Some additional formulas. A word of warning about the order of factors in unbalanced designs. An example with R. The interpretation of the model parameters and the lack of flexibility of the model: the need for interaction effects. The two-way ANOVA model with interaction effects: model equation and restrictions. The interpretation of the model parameters. The three F tests, their test statistics and distribution under H0. Interaction plots. Two examples with R. Some formulas.