Solutions Manual to Accompany Introduction to Linear Regression Analysis, 5th Edition

Chapter 3

Multiple Linear Regression

3.1 a. = −1.8 + .0036x₂ + .194x₇ − .0048x₈

b. Regression is significant.

c. All three are significant.

Coefficient	test statistic	p-value
β2	5.18	0.000
β7	2.20	0.038
β8	−3.77	0.001

d. R² = 78.6% and R²_Adj = 76.0%

e. F₀ = (257.094 − 243.03)/2.911 = 4.84 which is significant at α = 0.05. The test statistic here is the square of the t-statistic in part c.

3.2 Correlation coefficient between y_i and _i is .887. So (.887)² = .786 which is R².

3.3 a. A 95% confidence interval on the slope parameter β₇ is ₇ ± 2.064(.08823) = (.012, .376)

b. A 95%. confidence interval on the mean number of games won by a team when x₂ = 2300, x₇ = 56.0 and x₈ = 2100 is

3.4 a. = 17.9 + .048x₇ − .00654x₈ with F = 15.13 and p = 0.000 which is significant.

b. R² = 54.8% and R²_Adj = 51.5% which are much lower.

c. For β₇, a 95% confidence interval is 0.484 ± 2.064(.1192) ...