11/1/2011

Chapter 8 Polynomial Regression Models

• To avoid problems with multicollinearity, center the predictor variables - see Powercell.R

Interaction Regression Models - (see Figure 8.8 on p. 310)

• Additive model (no interaction)
• Reinforcement interaction effect
• Interference interaction effect

Regression models with qualitative predictors

• Formal model
• Example with RStudio - see Firms.R

Please read Chapter 9 for class on Thursday.