On a graph, you may notice a straight line going over all of your data. This is a trend line, and makes a nice, straight line out of your data. We call this a trend line because it can help determine what's happening on your system - what are the current trends?
Add a Trend Line
If you do not see a trend line, right-click in your data and choose Show Trend Line.
You can start/end your trend line anywhere on your data by dragging the ends of the trend line, or right-clicking on a date and choosing Start Trends Here or End Trends Here.
Clicking once on the trend line opens up the trend statistics window, which show info like minimum, maximum, average and growth.
The Extrapolation tab lets you use the current slope of the trend line to extrapolate into the future - when looking at a graph by month or week, enter the number of months or weeks in the appropriate field and click Extrapolate. You will then see a graph that projects the current trend into the future. To stop seeing the extrapolation on the graph, click the Extrapolate button again.
You can also split trend lines to compare two different date ranges. Right-click on the trend line and choose Split Trend Line. You can manipulate each piece by dragging the end points, or grabbing the middle and dragging the entire line. Clicking on one of the trend lines will open the trend statistics window. There is a Before vs After tab in the window, where you can compare the statistics of each segment.
As long as the two split trend lines are not overlapping, you can right-click and choose Before vs After to do an analysis.
To re-join the trend lines, right-click and choose Join Trend Line.