Question
Predictor Coefficient
Intercept 1225
FloorSpace 11.52
CompetingAds −6.935
Price −0.1496
13.4 Refer to the ANOVA table for this regression. (a) State the degrees of freedom for the F test for overall significance. (b) Use Appendix F to look up the critical value of F for α = .05. (c) Calculate the F statistic. Is the regression significant overall? (d) Calculate R2 and R2adj, showing your formulas clearly.
Source d.f. SS MS
Regression 3 1,196,410 398,803
Error 26 379,332 14,590
Total 29 1,575,742
13.6 Observations are taken on sales of a certain mountain bike in 30 sporting goods stores. Theregression model was Y = total sales (thousands of dollars), X1 = display floor space (square meters), X2 = competitors’ advertising expenditures (thousands of dollars), X3 = advertised price (dollars per unit), X4 = rebate rate (percent of retail price). (a) Calculate the t statistic for each coefficient to test for β = 0. (b) Look up the critical value of Student’s t in Appendix for a two-tailed test at α = .01. Which coefficients differ significantly from zero? (c) Use Excel to find the p-value for each coefficient.
Predictor Coefficient SE
Intercept 1225.4 397.3
FloorSpace 11.522 1.330
CompetingAds −6.935 3.905
Price −0.14955 0.08927
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