Chapter 13:
Nonlinear and Multiple Regression
395
4.
a.
The (x, residual) pairs for the plot are (0, -.335), (7, -.508), (17. -.341), (114, .592), (133,
.679), (142, .700), (190, .142), (218, 1.051), (237, -1.262),
and (285, -.719).
The plot
shows substantial evidence of curvature.
b.
The standardized residuals (in order corresponding to increasing x) are -.50, -.75, -.50,
.79, .90, .93, .19, 1.46, -1.80, and -1.12.
A standardized residual plot shows the same
pattern as the residual plot discussed in the previous exercise.
The z percentiles for the
normal probability plot are –1.645, -1.04, -.68, -.39, -.13, .13, .39, .68, 1.04, 1.645.
The
plot follows.
The points follow a linear pattern, so the standardized residuals appear to
have a normal distribution.
2
1
0
-1
-2
1
0
-1
-2
percentile
std resid
Normal Probability Plot for the Standardized Residuals
5.
a.