3.9 Extensions

  • Interaction / Synergy effects

    Include a product term to account for synergy where one changes in one variable changes the association of the Y with another:

Y=β0+β1X1+β2X2+β3X1X2+ϵi

  • Non-linear relationships (e.g. polynomial fits)

Y=β0+β1X+β2X2+...βnXn+ϵi