Multiple choice: Interpret indicator In the model µ y = α + β 1 x 1 + β 2 x 2 , suppose that x 1 is an indicator variable for smoking, equalling 1 for smokers and 0 for nonsmokers.  a. We set x 1 = 0...

Multiple choice: Interpret indicator In the model µ_y
= α + β₁x₁
+ β₂x₂, suppose that x₁
is an indicator variable for smoking, equalling 1 for smokers and 0 for nonsmokers.

 a. We set x₁
= 0 if we want a predicted mean without knowing if the person is a smoker or not.

b. The slope effect of x₂
is β₁
for smokers and β₂
for nonsmokers.

c. β₁
is the difference between the population mean of y for smokers and nonsmokers.

d. β₁
is the difference between the population mean of y for smokers and nonsmokers, for all those subjects having x₂
fixed, such as x₂
= 10.