MG 620 Statistics for Managers Homework Assignment Week 12 Chapter 13: Regression Analysis Instruction: The use of PHSTAT2 package is not necessary. It is only a guide. If you use it please report and interpret your answer in separate parts per question. Question 13.4 , page 481 The marketing manager of a large supermarket chain would like to use shelf space to predict the sales of pet food. A random sample of 12 equalized stores is selected, with the following results. Store 1 2 3 4 5 6 7 8 9 10 11 12 Shelf Space(X) 5 5 5 10 10 10 15 15 15 20 20 20 Weekly sales(Y) 160 220 140 190 240 260 230 270 280 260 290 310 a) Construct a scatter plot. For these data, b0 = 145 and b1 = 1 7.4 b) Interpret the meaning of the slope, b1, in this problem c) Predict the weekly sales of pet food for stores with 8 feet of shelf space for pet food. Question 13.16, page 487 In Problem 13.4 on page 481, the marketing manager used shelf for pet food to predict weekly sales (stored in Petfood). For those data SSR = 20,535 and SST = 30,025 a. Determine the coefficient of determination, r2, and interpret its meaning. b. Determine the standard error of the estimate. c. How useful do you think this regression model is for predicting sales 1 MG 620 Statistics for Managers Homework Assignment Week 11 Chapter 13 Instruction: The use of PHSTAT2 package or excel is not necessary. It is only a guide. If you use it please report and interpret your answer in separate parts per question. Question 1 Management of a soft-drink bottling company has the business objective of developing a method for allocating delivery costs to customers. Although one cost clearly relates to travel time within a particular route, another variable cost reflects the time. To begin, management decided to develop a regression model to predict delivery time based on the number of cases delivered. A sample of 20 deliveries within a territory was selected. The delivery times and the number of cases delivered were organized in the following table. Customers Number of Cases 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 52 64 73 85 95 103 116 121 143 157 161 184 202 218 243 254 267 275 287 298 a) b) c) d) Delivery Time (minutes) 32 35 36 38 38 40 39 42 44 47 43 49 57 57 61 61 58 63 66 67 What is the dependent variable? Why? Label it as Y and find its mean value What is the independent variable? Why? Construct a scatter plot. Hint: see page 430 For these data, b0 = 124.84 and b1 = 0.14. Interpret the meaning of b0 and b1 in this problem. e) What is the predicted line in this problem? Hint: See page 43 or 432 2 f) Predict the mean delivery time for 150cases of soft drink? Question 2 If SSR = 66 and SST = 88: a. Determine the coefficient of determination, r2, and interpret its meaning. Show your work b. Determine the standard error of estimate, if the sample size = 50. Show your work c. How useful do you think this regression model is for predicting sales? Explain