Click on the Forecast Accuracy icon on the Reports tab to open the Forecast Accuracy report. TheForecast Accuracy report looks at previously generated forecasts vs. what actually happened.
The Comparison section at the top of the dialog box is where you define the type of Forecast(s) you want to use (Baseline, Forecast, Statistical) and the lead time you want to compare to. A lead time refers to the number of periods ahead of the forecast origin (the period when the forecast is generated) the forecast was made for. Thus, a one-month-ahead forecast would have lead time equals 1, a two-month-ahead forecast would have lead time equals 2, etc. By default, the report compares the forecast we made last period (Forecast(L1)) to what actually happened for the current month only.