COMPONENTS

Area Charts

Area charts are sometimes referred to as a filled line or surface graph. It is ideal for adding emphasis to a dataset by virtue of shading or color. For multiple datasets there is also the option of a Stacked Area chart.

Area Chart

DO

  • Use transparency to make the chart easy to read and avoid obscuring the grid.
  • On the y-axis, choose increments that are easy to follow. All values on the y-axis must be divisible by the increment itself.
  • Always include a zero baseline on the y-axis. An Area graph that doesn't include a zero baseline is misleading.
  • Choose a time period that encompasses reference points that add perspective to the data.
  • Always label your axes and include the units for the y-axis.
  • The zero baseline should be thicker than the rest of the grid lines.
  • The legend is the key to the information. It should be positioned above or to the left of the graph and in the same order as the sequence of the components.

DON'T

  • Don't use negative values.
  • Don't position the legend below the chart.
Stacked Area Chart

DO

  • Choose a time period that encompasses reference points that add perspective to the data.
  • Always label your axes and include the units for the y-axis.
  • On the y-axis, choose increments that are easy to follow. All values on the y-axis must be divisible by the increment itself.
  • Ideal increments (0,5,10,15,20,25 / 0,1,2,3,4,5 / 0,2,4,6,8,10 / 0,10,20,30,40,50 / 0,0.25,0.50,0.75,1.00,1.25 / 0,0.2,0.4,0.6,0.8,1.0)
  • Awkward increments (0,3,6,9,12,15 / 0,7,14,21,28,35,42 / 0,0.4,0.8,1.2,1.6,2.0 / 3,5,7,9,11)
  • Always include a zero baseline on the y-axis. A Stacked Area graph that doesn't include a zero baseline is misleading.
  • The zero baseline should be thicker than the rest of the grid lines.
  • The legend is the key to the information. It should be positioned above or to the left of the graph and in the same order as the sequence of the components.
  • Add each area to the one below.
  • The top of the upper data series represents the total.

DON'T

  • Don't use negative values.
  • Don't position the legend below the chart.
  • Don't overlap areas.