Exercise Questions: Applied Statistics in Business and Economics by Doane and Seward
Prepare answers to the following assignments from the e-text, _Applied Statistics in Business and Economics_, by Doane and Seward:
Chapter 12
CHAPTER REVIEW #1
Chapter Exercises 12.48 and 12.50
Chapter 13
Chapter Exercises 13.30 and 13.32
Chapter 14
Chapter Exercise 14.16
CHAPTER 12
CHAPTER REVIEW #1
LIST TWO LIMITATIONS OF BIVARIATE REGRESSION.
Often simplistic (multiple relationships usually exist.
Biased estimates, even if relevant predictors are omitted.
WHY IS ESTIMATING A MULTIPLE REGRESSION MODEL JUST AS EASY AS BIVARIATE REGRESSION?
Because a computer does all the calculations so there is no extra computational burden.
CHAPTER EXERCISES:
12.48
IN THE FOLLOWING REGRESSION, _X_ = WEEKLY PAY, _Y_ = INCOME TAX WITHHELD, AND _N_ = 35 MCDONALD'S EMPLOYEES. (A) WRITE THE FITTED REGRESSION EQUATION. (B) STATE THE DEGREES OF FREEDOM FOR A TWO-TAILED TEST FOR ZERO SLOPE, AND USE APPENDIX D TO FIND THE CRITICAL VALUE AT _Α_ = .05. (C) WHAT IS YOUR CONCLUSION ABOUT THE SLOPE? (D) INTERPRET THE 95 PERCENT CONFIDENCE LIMITS FOR THE SLOPE. (E) VERIFY THAT _F_ = _T_2 FOR THE SLOPE. (F) IN YOUR OWN WORDS, DESCRIBE THE FIT OF THIS REGRESSION.
R2 0.202
STD. ERROR 6.816
N 35
ANOVA TABLE
_SOURCE SS DF MS F P-VALUE_
REGRESSION 387.6959 1 387.6959 8.35 .0068
RESIDUAL 1,533.0614 33 46.4564
TOTAL 1,920.7573 34
REGRESSION OUTPUT _CONFIDENCE INTERVAL_
_VARIABLES COEFFICIENTS STD. ERROR T (DF_ = _33) P-VALUE 95% LOWER 95% UPPER_
INTERCEPT 30.7963 6.4078 4.806 .0000 17.7595 43.8331
SLOPE 0.0343 0.0119 2.889 .0068 0.0101 0.0584
(A) WRITE THE FITTED REGRESSION EQUATION.
y = 0.0343x + 30.7963
(B) STATE THE DEGREES OF FREEDOM FOR A TWO-TAILED TEST FOR ZERO SLOPE, AND USE APPENDIX D TO FIND THE CRITICAL VALUE AT _Α_ = .05.
Dof = 35 - 1 = 34, critical value of t corresponding to 34 dof at ( = 0.05 (two-tailed) is 2.032.
(C) WHAT IS YOUR CONCLUSION ABOUT THE SLOPE?
Since the t- value for the slope (2.889) is greater than the critical value (2.032), the null
Chapter 12
CHAPTER REVIEW #1
Chapter Exercises 12.48 and 12.50
Chapter 13
Chapter Exercises 13.30 and 13.32
Chapter 14
Chapter Exercise 14.16
CHAPTER 12
CHAPTER REVIEW #1
LIST TWO LIMITATIONS OF BIVARIATE REGRESSION.
Often simplistic (multiple relationships usually exist.
Biased estimates, even if relevant predictors are omitted.
WHY IS ESTIMATING A MULTIPLE REGRESSION MODEL JUST AS EASY AS BIVARIATE REGRESSION?
Because a computer does all the calculations so there is no extra computational burden.
CHAPTER EXERCISES:
12.48
IN THE FOLLOWING REGRESSION, _X_ = WEEKLY PAY, _Y_ = INCOME TAX WITHHELD, AND _N_ = 35 MCDONALD'S EMPLOYEES. (A) WRITE THE FITTED REGRESSION EQUATION. (B) STATE THE DEGREES OF FREEDOM FOR A TWO-TAILED TEST FOR ZERO SLOPE, AND USE APPENDIX D TO FIND THE CRITICAL VALUE AT _Α_ = .05. (C) WHAT IS YOUR CONCLUSION ABOUT THE SLOPE? (D) INTERPRET THE 95 PERCENT CONFIDENCE LIMITS FOR THE SLOPE. (E) VERIFY THAT _F_ = _T_2 FOR THE SLOPE. (F) IN YOUR OWN WORDS, DESCRIBE THE FIT OF THIS REGRESSION.
R2 0.202
STD. ERROR 6.816
N 35
ANOVA TABLE
_SOURCE SS DF MS F P-VALUE_
REGRESSION 387.6959 1 387.6959 8.35 .0068
RESIDUAL 1,533.0614 33 46.4564
TOTAL 1,920.7573 34
REGRESSION OUTPUT _CONFIDENCE INTERVAL_
_VARIABLES COEFFICIENTS STD. ERROR T (DF_ = _33) P-VALUE 95% LOWER 95% UPPER_
INTERCEPT 30.7963 6.4078 4.806 .0000 17.7595 43.8331
SLOPE 0.0343 0.0119 2.889 .0068 0.0101 0.0584
(A) WRITE THE FITTED REGRESSION EQUATION.
y = 0.0343x + 30.7963
(B) STATE THE DEGREES OF FREEDOM FOR A TWO-TAILED TEST FOR ZERO SLOPE, AND USE APPENDIX D TO FIND THE CRITICAL VALUE AT _Α_ = .05.
Dof = 35 - 1 = 34, critical value of t corresponding to 34 dof at ( = 0.05 (two-tailed) is 2.032.
(C) WHAT IS YOUR CONCLUSION ABOUT THE SLOPE?
Since the t- value for the slope (2.889) is greater than the critical value (2.032), the null