Difference… charts compare two or more time-series. The second series in each pair is subtracted from the first series, and the difference is plotted over time. A positive value indicates that the upper time series is larger than the lower time series in a particular year, and vice-versa.

To analyse the difference between two or more time series:

1. Open the [Charts] menu and select [Difference…],
   …or click on the icon on the toolbar.
2. Select the data for analysis in the Difference form. Choose the simulation(s) you wish to analyse in the upper selection window, and the data you wish to analyse in the lower window.

For example, a comparison of sowing dates shows which years the earlier sowing date yielded more or less than the later sowing date.