statistics, a forecast error is the difference between the actual or real and the predicted or forecastvalue of a time seriesor any other phenomenon of interest.
In simple cases, a forecast is compared with an outcome at a single time-point and a summary of forecast errors is constructed over a collection of such time-points. Here the forecast may be assessed using the difference or using a proportional error. By convention, the error is defined using the value of the outcome "minus" the value of the forecast.
In other cases, a forecast may consist of predicted values over a number of lead-times; in this case an assessment of forecast error may need to consider more general ways of assessing the match between the time-profiles of the forecast and the outcome. If a main application of the forecast is to predict when certain thresholds will be crossed, one possible way of assessing the forecast is to use the timing-error—the difference in time between when the outcome crosses the threshold and when the forecast does so. When there is interest in the maximum value being reached, assessment of forecasts can be done using any of:
* the difference of times of the peaks;
* the difference in the peak values in the forecast and outome;
* the difference between the peak value of the outcome and the value forecast for that time point.
Forecast error can be a calendar forecast error or a cross-sectional forecast error, when we want to summarize the forecast error over a group of units. If we observe the average forecast error for a time-series of forecasts for the same product or phenomenon, then we call this a calendar forecast error or time-series forecast error. If we observe this for multiple products for the same period, then this is a cross-sectional performance error.
Calculating Demand Forecast Accuracy
Mean squared prediction error
Errors and residuals in statistics
Wikimedia Foundation. 2010.
Look at other dictionaries:
Forecast — Die Prognose (griechisch, πρóγνωσις – wörtlich „das Vorwissen“, die „Voraus Kenntnis“), deutsch Vorhersage oder Voraussage, selten auch: Prädiktion (lat. praedicare „ im Voraus“ und „sagen“) bezeichnet die Aussagen über Ereignisse, Zustände oder… … Deutsch Wikipedia
Calculating Demand Forecast Accuracy — upply Chain forecastingUnderstanding customer demand is key to any manufacturer to make and keep sufficient long lead inventory so that customer orders can be correctly met. Forecasts are never perfect but are valuable in better preparedness for… … Wikipedia
Mean absolute scaled error — In statistics, the mean absolute scaled error (MASE) is a measure of the accuracy of forecasts . It was proposed in 2006 by Australian statistician Rob Hyndman, who described it as a generally applicable measurement of forecast accuracy without… … Wikipedia
Mean percentage error — In statistics, the mean percentage error (MPE) is the computed average of percentage errors by which estimated forecasts differ from actual values of the quantity being forecast. Formula for mean percentage error calculation is: where at is the… … Wikipedia
Tropical cyclone forecast model — [ National Hurricane Center (NHC)] A tropical cyclone forecast model is a computer program that uses meteorological data to forecast the motion and intensity of tropical cyclones. Such models utilize powerful supercomputers with sophisticated… … Wikipedia
Mean absolute percentage error — (MAPE) is measure of accuracy in a fitted time series value in statistics, specifically trending. It usually expresses accuracy as a percentage, and is defined by the formula: where At is the actual value and Ft is the forecast value. The… … Wikipedia
Mean absolute error — In statistics, the mean absolute error (MAE) is a quantity used to measure how close forecasts or predictions are to the eventual outcomes. The mean absolute error is given by As the name suggests, the mean absolute error is an average of the… … Wikipedia
Demand sensing — is a next generation forecasting method that leverages new mathematical techniques and near real time information to create an accurate forecast of demand, based on the current realities of the supply chain. The typical performance of demand… … Wikipedia
Forecasting — is the process of estimation in unknown situations. Prediction is a similar, but more general term. Both can refer to estimation of time series, cross sectional or longitudinal data. Usage can differ between areas of application: for example in… … Wikipedia
Weather forecasting — weather forecaster redirects here. For other uses, see Weatherman (disambiguation). Forecast of surface pressures five days into the future for the north Pacific, North America, and north Atlantic ocean. Weather forecasting is the application of… … Wikipedia