Which Residual Plot Would You Examine to Determine Whether the Assumption

Multiple Choice

Which residual plot would you examine to determine whether the assumption of constant error variance is satisfied for a model with two independent variables $x _ { 1 }$ and $x _ { 2 }$ ?

A) Plot the residuals against observed $y$ values.
B) Plot the residuals against the independent variable $x _ { 2 }$ .
C) Plot the residuals against the independent variable $x _ { 1 }$ .
D) Plot the residuals against predicted values, $\hat { y }$ .