Trend Lines are lines that connect two or more points and then extend into the future to assist in detecting and predicting trends in time-series data. To display Trend Lines select [Analysis > Show Trend Lines]. Trend Lines display as black lines overlaid on the current view and are dashed when shown over Line Charts and solid when shown over bar charts to prevent confusing them with original chart content. You can also edit Trend Line Options with [Analysis > Trend Lines > Edit Trend Lines...] when [Analysis > Trend Lines > Show Trend Lines] is enabled. 

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Once a Trend Line or Lines are displayed you can view slope and y-intercept for all the displayed Trend Lines by selecting [Analysis > Trend Lines > Describe Trend Model...].

If there are multiple lines, it is possible to show individual Trend Lines per line color by selecting [Analysis > Trend Lines > Edit Trend Lines...> Allow a trend line per color].

Once [Allow a trend line per color] is enabled in the Trend Options dialog, each Trend Line will have a dashed line the same color as the line it is trending to make identifying them easier.

If Trend Line Per Color is enabled for a Multi-Line Chart, selecting [Analysis > Trend Lines > Describe Trend Model...] will produce Trend Line Details for every Trend Line visible in your chart. 

Edit Trend Line Options

You can select Trend Line options by choosing [Analysis > Trend Lines > Edit Trend Lines...] which launches the Trend Line Options dialog.

From this dialog, you can select the Trend Line Model Type as:

  • Linear
  • Logarithmic
  • Exponential
  • Polynomial, degree (and choose the value for degree)

Options within the Trend Line Options dialog also allow for

  • including fields as factors (with the Dimensions listed from your decks)
  • enabling/disabling trend line per color
  • showing confidence bands
  • forcing y-intercept to zero.


If you plot chart using a trend line and select specific data points in the view, Visual Analytics compares the data for the selected data points and plots a recalculated line for the highlighted data while dimming the original line.
 
The following example originally showed the order date by freight. When you select October through December, Visual Analytics instantly compares the order date for these months and plots a recalculated line for the same. Now you can view freight for the last three months to the overall total quantity ordered new for each customer segment.

You can also control from where the trend line should start. In the Time Series Options area, you can set one of the following options:

  • Begin trend at first data point: Shows a trend from the epoch date (Jan 1, 1970).
  • Begin trend at zero: Shows a trend from first data point on the axis.

Other Actions

Other actions that you can perform on a plotted trend lines are as follows:

  • You can sort data by using various sort options available in the chart view or the Advanced dialog. For more information, see Sorting.
  • You can use highlight actions to focus on selected trend lines. Visual Analytics makes the highlighted trend lines prominent while dimming others in the view. For more information, see Highlight Actions.
  • You can export worksheets containing visualization to Image, HTML, and PDF formats. For more information, see Export Visualizations.



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