Consider the inverter data in Exercise 12-110. Delete

Chapter 12, Problem 111SE

(choose chapter or problem)

Consider the inverter data in Exercise 12-110. Delete observation 2 from the original data. Define new variables as follows:

                                      \(y^{*}=\ln y, x_{1}^{*}=1 / \sqrt{x_{1}} x_{2}^{*}=\sqrt{x_{2}} x_{3}^{*}=1 / \sqrt{x_{3}}, \text { and } x_{4}^{*}=\sqrt{x_{4}}\)

(a) Fit a regression model using these transformed regressors (do not use \(x_{5}\) or \(x_{5}\) ).

(b) Test the model for significance of regression using \(\alpha=0.05\). Use the \(t \text {-test }\) to investigate the contribution of each variable to the model \((\alpha=0.05)\). What are your conclusions?

(c) Plot the residuals versus \(\hat{\mathrm{y}}^{*}\) and versus each of the transformed regressors. Comment on the plots.

Equation Transcription:

test

Text Transcription:

y^*=ln y,x_1^*=1/sqrt x_1,x2*=sqrt x_2,x_3*=1/sqrt x_3, and x_4 ^*=sqrt x_4

x_5

x_6

a=0.05

t-test

(a=0.05)

hat y*