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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Port of Baltimore Exponential Smoothing Example QtrActual Tonnage Unloaded Rounded Forecast 1180175 2168 3159 4175 5190 6205 7180 8182 9?
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Port of Baltimore Exponential Smoothing Example QtrActual Tonnage Unloaded Rounded Forecast using =0.10 1180175 2168176= 175.00+0.10(180-175) 3159175 =175.50+0.10(168-175.50) 4175173 =174.75+0.10(159-174.75) 5190173 =173.18+0.10(175-173.18) 6205175 =173.36+0.10(190-173.36) 7180178 =175.02+0.10(205-175.02) 8182178 =178.02+0.10(180-178.02) 9? 179= 178.22+0.10(182-178.22)
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Port of Baltimore Exponential Smoothing Example QtrActual Tonnage Unloaded Rounded Forecast using =0.50 1180175 2168178 =175.00+0.50(180-175) 3159173 =177.50+0.50(168-177.50) 4175166 =172.75+0.50(159-172.75) 5190170 =165.88+0.50(175-165.88) 6205180 =170.44+0.50(190-170.44) 7180193 =180.22+0.50(205-180.22) 8182186 =192.61+0.50(180-192.61) 9? 184 =186.30+0.50(182-186.30)
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Port of Baltimore Exponential Smoothing Example To evaluate the accuracy of each smoothing constant, we can compute the absolute deviations and MADs.
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Selecting a Smoothing Constant
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Port of Baltimore Exponential Smoothing Example Based on this analysis, a smoothing constant of =0.10 is preferred to =0.50 because its MAD is smaller.
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Trend Projections A trend line is simply a linear regression equation in which the independent variable (X) is the time period. The form is a = - b
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Example/ Midwestern Manufacturing Company Let us consider the case of Midwestern Manufacturing Company. That firm's demand for electrical generators over the period 1996- 2002 is shown in the table below: YearSales 199674 199779 199880 199990 2000105 2001142 2002122
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Example/ Midwestern Manufacturing Company A trend line to predict demand (Y) based on the period can be developed using a regression model. We let 1996 be time period 1 (X = 1) then 1997 is time period 2 (X = 2), and so forth. YearTimeSales 1996174 1997279 1998380 1999490 20005105 20016142 20027122
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Example/ Midwestern Manufacturing Company Time period Generator demand XY 1 741 2 794158 3 809240 4 9016360 5 10525525 6 14236852 712249854
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To accompany Quantitative Analysis for Management, 8e by Render/Stair/Hanna Example/ Midwestern Manufacturing Company a = 98.86- 10.54(4)=56.7 Hence, the least squares trend equation is Y= 56.70 + 10.54 X. To project demand in 2003, we first denote the year 2003 in our new coding system as X = 8 (sales in 2003) = 56.7 + 10.54 (8) = 141 generators (sales in 2004) = 56.7 + 10.54 (9) = 152 generators
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