1. A computer-implemented method for determining a confidence interval for a forecasted behavior value associated with a current time point, the method comprising: defining, by a computer, a plurality of historical periods each having a plurality of discrete time points; determining, by the computer, a target behavior value for each historical period; generating, by the computer, a forecast series for each historical period, the forecast series including forecasts of the target behavior value at the discrete time points of the historical period; generating, by the computer, a forecast error series for each historical period as a function of the forecast series and the target behavior value of the historical period; forming, by the computer, an error distribution series from pooled values of the forecast error series over the plurality of historical periods; generating, by the computer, a forecast error distribution as a function of the error distribution series and the current time point; determining, by the computer, the confidence interval of the forecasted behavior value from the forecast error distribution.