Binary/categorical X

Question 1

Transformations

Answer 1

Log -> absolute values
Sqrt -> count data
Arcsin -> proportions/percentages

Question 2

Assumptions

Answer 2

a) The expected value of each residual εi is 0: E (εi ) = 0.
b) All εi have the same variance: Var(εi) = σ2.
c) The εi are normally distributed.
d) The εi are independent of each other.

Question 3

If assumptions are violated

Answer 3

• Transform any/all x or y
• look for outliers
• add more terms or interactions
• use other model