17,18,19
CHAPTER 5. FORECASTING 5-17 Data collected on the yearly demand for 50-pound bags of fertilizer at Wallace Garden Supply are shown in the following table. Develop a 3-year mov- ing average to forecast sales. Then estimate demand again with a weighted moving average in which sales in the most recent year are given a weight of 2 and sales in the other 2 years are each given a weight of 1. Which method do you think is best? YEAR DEMAND FOR FERTILIZER (1.000 OF BAGS) 4 1 2 3 4 5 5 6 6 7 7 8 6 4 5 5 10 8 7 9 12 10 11 15 5-18 Develop a trend line for the demand for fertilizer in Problem 5-17, using any computer software. 5-19 In Problems 5-17 and 5-18, three different fore. casts were developed for the demand for fertilizer. These three forecasts are a 3-year moving average. a weighted moving average, and a trend line. Which one would you use? Explain your answer. 5-20 Use exponential smoothing with a smoothing con- stant of 0.3 to forecast the demand for fertilizer given in Problem 5-17. Assume that last period's forecast for year 1 is 5,000 bags to begin the pro- cedure. Would you prefer to use, the exponential smoothing model or the weighted average model developed in Problem 5-17? Explain your answer. 5-21 Sales of Cool-Man air conditioners have grown steadily during the past 5 years: :5-23 What effect did the smoothing constant have on the forecast for Cool-Man air conditioners? (See Poh lems 5-21 and 5-22.) Which smoothing con gives the most accurate forecast? 5-24 Use a three-year moving average forecasting model to forecast the sales of Cool-Man air conditioners (see Problem 5-21). 2.5-25 Using the trend projection method, develop a for casting model for the sales of Cool-Man air con tioners (see Problem 5-21). : 5-26 Would you use exponential smoothing with smoothing constant of 0.3, a 3-year moving average or a trend to predict the sales of Cool-Man air condi tioners? Refer to Problems 5-21, 5-24, and 5-25 : 5-27 Sales of industrial vacuum cleaners at R. Lowenthal Supply Co. over the past 13 months are as follows: SALES ($1.000) MONTH SALES ($1,000) MONTH 11 January 14 August 14 February 17 September 16 March 12 October 10 14 April November 15 May 16 December 17 June 11 January 11 July (a) Using a moving average with three periods. determine the demand for vacuum cleaners for next February (b) Using a weighted moving average with three periods, determine the demand for vacuum cleaners for February. Use 3, 2, and 1 for the weights of the most recent, second most recent and third most recent periods, respectively. For example, if you were forecasting the demand for February, November would have a weight of 1, December would have a weight of 2, and January would have a weight of 3. (c) Evaluate the accuracy of each of these methods. (d) What other factors might R. Lowenthal consider in forecasting sales? 8:5-28 Passenger miles flown on Northeast Airlines, a com muter firm serving the Boston hub, are as follows for the past 12 weeks: ACTUAL PASSENGER ACTUAL PASSENGER WEEK MILES (1,000) WEEK MILES (1.000 1 17 7 20 2 21 8 18 3 19 9 4 23 10 20 5 18 11 15 6 16 12 (a) Assuming an initial forecast for week 1 of 17,000 miles, use exponential smoothing to compute miles for weeks 2 through 12. Use a = 0.2 YEAR SALES 450 1 495 518 2 3 4 5 6 563 584 ? The sales manager had predicted, before the business started, that year I's sales would be 410 air condi- tioners. Using exponential smoothing with a weight of a = 0.30, develop forecasts for years 2 through 6. 5-22 Using smoothing constants of 0.6 and 0.9, develop forecasts for the sales of Cool-Man air conditioners (see Problem 5-21). 22 CHAPTER 5. FORECASTING 5-17 Data collected on the yearly demand for 50-pound bags of fertilizer at Wallace Garden Supply are shown in the following table. Develop a 3-year mov- ing average to forecast sales. Then estimate demand again with a weighted moving average in which sales in the most recent year are given a weight of 2 and sales in the other 2 years are each given a weight of 1. Which method do you think is best? YEAR DEMAND FOR FERTILIZER (1.000 OF BAGS) 4 1 2 3 4 5 5 6 6 7 7 8 6 4 5 5 10 8 7 9 12 10 11 15 5-18 Develop a trend line for the demand for fertilizer in Problem 5-17, using any computer software. 5-19 In Problems 5-17 and 5-18, three different fore. casts were developed for the demand for fertilizer. These three forecasts are a 3-year moving average. a weighted moving average, and a trend line. Which one would you use? Explain your answer. 5-20 Use exponential smoothing with a smoothing con- stant of 0.3 to forecast the demand for fertilizer given in Problem 5-17. Assume that last period's forecast for year 1 is 5,000 bags to begin the pro- cedure. Would you prefer to use, the exponential smoothing model or the weighted average model developed in Problem 5-17? Explain your answer. 5-21 Sales of Cool-Man air conditioners have grown steadily during the past 5 years: :5-23 What effect did the smoothing constant have on the forecast for Cool-Man air conditioners? (See Poh lems 5-21 and 5-22.) Which smoothing con gives the most accurate forecast? 5-24 Use a three-year moving average forecasting model to forecast the sales of Cool-Man air conditioners (see Problem 5-21). 2.5-25 Using the trend projection method, develop a for casting model for the sales of Cool-Man air con tioners (see Problem 5-21). : 5-26 Would you use exponential smoothing with smoothing constant of 0.3, a 3-year moving average or a trend to predict the sales of Cool-Man air condi tioners? Refer to Problems 5-21, 5-24, and 5-25 : 5-27 Sales of industrial vacuum cleaners at R. Lowenthal Supply Co. over the past 13 months are as follows: SALES ($1.000) MONTH SALES ($1,000) MONTH 11 January 14 August 14 February 17 September 16 March 12 October 10 14 April November 15 May 16 December 17 June 11 January 11 July (a) Using a moving average with three periods. determine the demand for vacuum cleaners for next February (b) Using a weighted moving average with three periods, determine the demand for vacuum cleaners for February. Use 3, 2, and 1 for the weights of the most recent, second most recent and third most recent periods, respectively. For example, if you were forecasting the demand for February, November would have a weight of 1, December would have a weight of 2, and January would have a weight of 3. (c) Evaluate the accuracy of each of these methods. (d) What other factors might R. Lowenthal consider in forecasting sales? 8:5-28 Passenger miles flown on Northeast Airlines, a com muter firm serving the Boston hub, are as follows for the past 12 weeks: ACTUAL PASSENGER ACTUAL PASSENGER WEEK MILES (1,000) WEEK MILES (1.000 1 17 7 20 2 21 8 18 3 19 9 4 23 10 20 5 18 11 15 6 16 12 (a) Assuming an initial forecast for week 1 of 17,000 miles, use exponential smoothing to compute miles for weeks 2 through 12. Use a = 0.2 YEAR SALES 450 1 495 518 2 3 4 5 6 563 584 ? The sales manager had predicted, before the business started, that year I's sales would be 410 air condi- tioners. Using exponential smoothing with a weight of a = 0.30, develop forecasts for years 2 through 6. 5-22 Using smoothing constants of 0.6 and 0.9, develop forecasts for the sales of Cool-Man air conditioners (see Problem 5-21). 22
