Design Considerations for Trellis Views

Consider the following points when designing trellis views.

For all trellis views:

• For comparisons, select the Simple Trellis.

• For trend analysis, select the Advanced Trellis.

• Make the inner graphs that comprise a trellis readable and not too dense. A trellis view isn’t especially useful for displaying multiple series or multiple groups. If you can’t easily target a data point with the mouse (to display a tooltip), then the inner graph is likely too dense to be readable.

• For the Simple Trellis:

  • The total number of cells displayed is less than in a pivot table.

  • You can associate one or two of the dimensions with the visualization. You add fewer dimensions to the outer edge than in a pivot table.

  • Try to use a small number of outer-edge dimensions. The entire graph series should be visible at once (for easy comparison of like to like) with no need to scroll. If you must show additional dimensionality, then consider adding the dimensions to the graph prompt.

  • When determining which data to show in column headers and row headers, make sure that the column headers show one or two dimensions (each dimension with a small number of members).

• For the Advanced Trellis:

  • A common use case for an advanced trellis is to show trend graphs alongside numeric values, in a compressed form. So a typical advanced trellis contains a combination of spark graphs alongside number representations of the same measure.

  • Ideally, include no dimensions in the column headers. Include the measure in the column headers.

  • The dimensionality typically associated with a spark graph is time. Because a spark graph includes no visible labels, it’s important that the data visualized is intrinsically ordered. For example, a spark graph that visualizes regions is meaningless, because the ordering of the regions (which would be the specific bars, in a spark bar graph) isn’t intuitive.

  • Just as when designing pivot tables, you generally display time on the horizontal axis, with the other dimensions displayed on the vertical axis. The eye then scans from left to right to see how the dimensionality changes over time.

• Hierarchical columns don’t work well with the simple trellis. When a hierarchical column is displayed on the outer edge, parents and children (such as Year and Quarter) are shown by default using a common axis scale. However, because Year and Quarter have different magnitudes, the markers in child graphs might be extremely small and hard to read against the parent scale. (Hierarchical columns do work well with the advanced trellis, because each data cell is a different scale.)