(de)Faults in Excel Charting

I recently spoke at SQLBitsIII, and an aspect which went down well was a simple overview on how to make the most important aspect of a graph, namely the underlying data, the prime focus and clear and easy to read. I also had the opportunity to attend Stephen Few’s Information Visualisation Workshops in London, which I’d thoroughly recommend. Stephen also spent some time, as part of a much more detailed overall agenda, on how a typical default chart can be morphed into an effective display.

So it’s back to basics this week, and how to improve the standard, out of the box Excel chart. Unfortunately, despite it’s pervasiveness, the default chart settings, which many users will never stray from, are in the case of Office 2007 not ideal, and in earlier versions, pretty awful. In this piece I’ll outline a few simple steps which can turn the default visual delights of the Excel graph into something you need not be embarrassed to put on the projector.

I’m using ‘classic’ Excel as my start point, because it’s still the incumbent in most organisations (and also because it’s worse). The example is for column charts, but the majority of the tips are valid for any chart type. As our start point we have the unit sales data for 3 products across 6 countries, as a default Excel Column chart, below.

BadChart

 

 

 

 

 

Nice. It’s wrong in a lot of ways, but how many hundred times have you seen this or a version of this? It’s well trodden ground if you have read Tufte, Few at al, but the key recommendations to improve things are surprisingly simple, and quick to implement.

1) Remove the Clutter and noise

The purpose of the chart is to display the data of interest clearly and concisely. It’s not to distract the user with pretty shading or 3D effects etc. Although the default chart is no-frills, there are a number of items which are adding nothing, or have undue prominence, and in doing so detract from the overall goal.

  • The Plot Area
    • The grey background to the plot area adds nothing, so we remove it
    • The border on the plot area – remove it also (numerous studies have shown we only need two axes to effectively group and visualise data)
  • Gridlines
    • The default gridlines are black, too visually intense. They are there for reference when required, not the prime focus, so are best muted – set them to a light grey.

2) Axes and Legend

The axes frame the chart, and are a key point of reference; however they should not draw the focus from the chart itself. As with the gridlines, they should be toned down.

  • Change the default black font colour to charcoal / dark grey
  • Change the default axis colour from black to charcoal / dark grey
  • Typically reduce the font size to 8

Rules for the legend are similar to those for the axis

  • Change font from black to grey
  • Remove border or change it’s colour to very light grey
  • Typically reduce font size to 8
  • For a clustered column, my preference is for the Legend positioned at the bottom, and reading across in the display order of the columns.

3) Columns and colour

The black column borders add nothing, and as such should be removed, they are another form of Tufte’s ‘non-data ink’.

On to colour, and unfortunately Excel’s default chart fills are heavily saturated plum and wine with a light cream..  So I’d strongly suggest changing the chart colour palette. For column charts, there is typically a reasonable block of colour for each series, so the colour scheme shouldn’t be too bold, or it becomes an eyesore. You should aim for mid-intensity colours of similar saturation (unless one is intended to stand out), pastels tend to work well.

 

All the steps above are simple and fairly fast to action, with one exception, the colour scheme. Unless you already have pre-prepared palettes it’s possible to spend an age trying to get the ideal combination – remember the 80/20 rule!

GoodChart2

 

 

 

 

 

 

In my example above, which hopefully you’ll agree is an improvement, I’ve used the colour palette from our upcoming ‘Chart Tamer’ product. Chart Tamer is a lot more than just a colour palette, but that aspect has benefited from minds with much more expertise in colour than mine, and I’ll go with their choice over mine every time!

2 Replies to “(de)Faults in Excel Charting”

  1. I would love to see something like this example but with a secondary Y axis added. I work in a Hospital quality reporting department, and we often have some data we just try to cram into one graph…at the behest of others. A lot of the time we have a metric, along with a patient volume.

  2. Matt, I’m generally a little wary of dual scale axes as they can be confusing for anyone not very familiar with the numbers and their expected scale- I’d consider another chart immediately below, and positioned to share the x-axis categories to make it easy to compare the relative performance. That way you can still see comparison but there is less potential for confusion in the audience.

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