Measuring forecasting accuracy: The case of judgmental adjustments to SKU-level demand forecasts
Forecast adjustment commonly occurs when organizational forecasters adjust a statistical forecast of demand to take into account factors which are excluded from the statistical calculation. This paper addresses the question of how to measure the accuracy of such adjustments. We show that many existing error measures are generally not suited to the task, due to specific features of the demand data. Alongside the well-known weaknesses of existing measures, a number of additional effects are demonstrated that complicate the interpretation of measurement results and can even lead to false conclusions being drawn. In order to ensure an interpretable and unambiguous evaluation, we recommend the use of a metric based on aggregating performance ratios across time series using the weighted geometric mean. We illustrate that this measure has the advantage of treating over- and under-forecasting even-handedly, has a more symmetric distribution, and is robust.
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Volume (Year): 29 (2013)
Issue (Month): 3 ()
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- Rob J. Hyndman & Anne B. Koehler, 2005.
"Another Look at Measures of Forecast Accuracy,"
Monash Econometrics and Business Statistics Working Papers
13/05, Monash University, Department of Econometrics and Business Statistics.
- Fildes, Robert, 1992. "The evaluation of extrapolative forecasting methods," International Journal of Forecasting, Elsevier, vol. 8(1), pages 81-98, June.
- Syntetos, Aris A. & Boylan, John E., 2005. "The accuracy of intermittent demand estimates," International Journal of Forecasting, Elsevier, vol. 21(2), pages 303-314.
- Jim Hoover, 2006. "Measuring Forecast Accuracy: Omissions in Today's Forecasting Engines and Demand-Planning Software," Foresight: The International Journal of Applied Forecasting, International Institute of Forecasters, issue 4, pages 32-35, June.
- Donna F. Davis & John T. Mentzer & Teresa M. Mccarthy & Susan L. Golicic, 2006. "The evolution of sales forecasting management: a 20-year longitudinal study of forecasting practices," Journal of Forecasting, John Wiley & Sons, Ltd., vol. 25(5), pages 303-324.
- Rob J. Hyndman & Yeasmin Khandakar, 2007.
"Automatic time series forecasting: the forecast package for R,"
Monash Econometrics and Business Statistics Working Papers
6/07, Monash University, Department of Econometrics and Business Statistics.
- Hyndman, Rob J. & Khandakar, Yeasmin, 2008. "Automatic Time Series Forecasting: The forecast Package for R," Journal of Statistical Software, Foundation for Open Access Statistics, vol. 27(i03), pages -.
- Fildes, Robert & Goodwin, Paul & Lawrence, Michael & Nikolopoulos, Konstantinos, 2009. "Effective forecasting and judgmental adjustments: an empirical evaluation and strategies for improvement in supply-chain planning," International Journal of Forecasting, Elsevier, vol. 25(1), pages 3-23.
- Goodwin, Paul & Lawton, Richard, 1999. "On the asymmetry of the symmetric MAPE," International Journal of Forecasting, Elsevier, vol. 15(4), pages 405-408, October.
- Armstrong, J. Scott & Collopy, Fred, 1992. "Error measures for generalizing about forecasting methods: Empirical comparisons," International Journal of Forecasting, Elsevier, vol. 8(1), pages 69-80, June.
- Stephan Kolassa & Wolfgang Schütz, 2007. "Advantages of the MAD/Mean Ratio over the MAPE," Foresight: The International Journal of Applied Forecasting, International Institute of Forecasters, issue 6, pages 40-43, Spring.
- Philip Hans Franses & Rianne Legerstee, 2010. "Do experts' adjustments on model-based SKU-level forecasts improve forecast quality?," Journal of Forecasting, John Wiley & Sons, Ltd., vol. 29(3), pages 331-340.
- Zellner, Arnold, 1986. "A tale of forecasting 1001 series : The Bayesian knight strikes again," International Journal of Forecasting, Elsevier, vol. 2(4), pages 491-494.
- Carlos Robalo Marques & Pedro Duarte Neves & Luís Morais Sarmento, 2000.
"Evaluating Core Inflation Indicators,"
w200003, Banco de Portugal, Economics and Research Department.
- Robalo Marques, Carlos & Duarte Neves, Pedro & Morais Sarmento, Luis, 2003. "Evaluating core inflation indicators," Economic Modelling, Elsevier, vol. 20(4), pages 765-775, July.
- Pedro Duarte Neves & Luís Morais Sarmento & Carlos Robalo Marques, 1999. "Evaluating core inflation indicators," Economic Bulletin and Financial Stability Report Articles, Banco de Portugal, Economics and Research Department, pages -.
- Rob J. Hyndman, 2006. "Another Look at Forecast Accuracy Metrics for Intermittent Demand," Foresight: The International Journal of Applied Forecasting, International Institute of Forecasters, issue 4, pages 43-46, June.
- Makridakis, Spyros, 1993. "Accuracy measures: theoretical and practical concerns," International Journal of Forecasting, Elsevier, vol. 9(4), pages 527-529, December.
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