The mean absolute error (MAE) is also measured in the same units as the data, and is usually similar in magnitude to, but slightly smaller than, the root mean squared error. It is less sensitive to the occasional very large error because it does not square the errors in the calculation. The mathematically challenged usually find this an easier statistic to understand than the RMSE. MAE and MAPE (below) are not a part of standard regression output, however. They are more commonly found in the output of time series forecasting procedures, such as the one in Statgraphics. It is relatively easy to compute them in RegressIt: just choose the option to save the residual table to the worksheet, create a column of formulas next to it to calculate errors in absolute or absolute-percentage terms, and apply the AVERAGE function.