13.27 Exercise 13.21 gave data on x 5 nerve firing frequency and y 5 pleasantness rating when nerves were stimulated by a light brushing stoke on the forearm. The x values and the corresponding residuals from a simple linear regression are as follows:

Firing Frequency, x Standardized Residual 23 21.83 24 0.04 22 1.45 25 0.20 27 21.07 28 1.19 34 20.24 33 20.13 36 20.81 34 1.17

a. Construct a standardized residual plot. Does the plot exhibit any unusual features?

b. A normal probability plot of the standardized residuals follows. Based on this plot, do you think it is reasonable to assume that the error distribution is approximately normal? Explain.

Transcribed Image Text:

Normal score -1 0 -2.0 -1.5 -1.0 -0.5 0.0 Standardized residual 0.5 1.0 1.5