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Percentage Error: What Denominator?


  • Kesten Geeen
  • Len Tashman


This is the authors' second survey on the measurement of forecast error. They reported the results of their first survey in the Summer 2008 issue of Foresight (Green & Tashman, 2008). The question they asked in that survey was whether to define forecast error as Actual minus Forecast (A-F) or Forecast minus Actual (F-A). Respondents made good arguments for both of the alternatives. In the current survey, they asked how percentage forecast error should be measured. In particular, what should the denominator be when calculating percentage error? The resulting answers and comments are presented here. Copyright International Institute of Forecasters, 2009

Suggested Citation

  • Kesten Geeen & Len Tashman, 2009. "Percentage Error: What Denominator?," Foresight: The International Journal of Applied Forecasting, International Institute of Forecasters, issue 12, pages 36-40, Winter.
  • Handle: RePEc:for:ijafaa:y:2009:i:12:p:36-40

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    4. Forbes, Kevin F. & Zampelli, Ernest M., 2020. "Accuracy of wind energy forecasts in Great Britain and prospects for improvement," Utilities Policy, Elsevier, vol. 67(C).

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