Peltier Technical Services - Excel Charts and Programming
In More graphical propaganda, Andrew Gelman of the Statistical Modeling, Causal Inference, and Social Science blog shows some pie charts of recent Kenyan election results which he got from John Sides’ blog post, Election Fraud in Kenya in The Monkey Cage blog. The charts are awful; as Andrew notes, the colors change and the wedges are reordered. I’ve regraphed the data on a bar chart, which I think is much better.
Original Chart
Better Chart
In Line-XY Combination Charts I showed how to make a combination Line-XY chart. It is probably important to discuss the differences between line charts and XY charts. The documentation is not clear, and the names of the chart types are not helpful; in fact, they lead to confusion.
The icons in the Chart Type dialog and in the Chart Wizard do not help to clarify the situation. These are the icons for line charts and XY charts in the Excel 2003 dialogs; the Excel 2007 icons are not substantially different.
It is important to note that:
After selection of a chart type, the user is presented with a set of choices, and the default sub-type for the selected chart type is highlighted. Not all available formatting for these chart types is available through the Chart Type dialog. [Read more…] about Line Charts vs. XY Charts
In Partition Charts in Excel – alternative to pie charts [visualization hack], Chandoo offers a “partition chart” as an alternative to a pie chart. We all know pie charts are bad (don’t we???), so it’s good to look for alternatives. Here is part of Chandoo’s partition chart:
This chart uses conditional formatting to achieve the mottled appearance. It’s almost reminiscent of camouflage, partly because of the mottled colors, and partly because the information is well hidden. The colors cover 22%, 30%, and 48% of the area of the chart. Without looking at the legend of the full partition chart below, can you at a glance match up the colors with their associated proportions? I couldn’t, either.
Here is Chandoo’s complete chart, including the legend:
As I told Chandoo in a comment to his post:
While pie charts are somewhat ineffective at showing relative proportions, this partition chart is completely ineffective. If not for the legend, I would have guessed that the darkest color accounted for the largest, not the smallest, proportion. The pie at least puts all of its bits into one wedge per category, while the partition chart keeps all the bits separate, and they are scattered across the chart. It’s as if you spilled a package of M&Ms on the table and tried to determine the portions of each color.
Since there are only three categories, a pie chart isn’t a terrible choice for this data:
As always, the simplest and clearest way to show this data is in a bar or column chart:
Chandoo spoke of the partition chart as a way to look at geographic variations in data. He mentioned that it might be sales of your products in a number of cities. It makes more sense if you were looking at a map of counties, states, regions, or countries, and you were filling each geographical unit’s shape with the fill color. The user would not be expected to integrate the entire map to get an overall percentage. Instead the user could compare the colors of familiar shaped geographical units and make sense of the data. Wikipedia has some examples of this in Red states and blue states:
In this context, regions of different colors can effectively present information about, in this case, election results in different states. In contrast, the partition graph is a map of nothing.
In Bad Graphics – Stacked Pyramid Chart, I critiqued a popular infographic display type, the pyramid chart. In this post I will repeat the favor for funnel charts. These are not the funnel charts which are also called tornado charts, and in some circles are used to construct population pyramids (see Tornado Charts and Tornado Charts and Dot Plots elsewhere on PeltierTech.com). These are stacked 3D abominations which sometimes follow a flawed analogy to a physical funnel, just like the pyramid charts in my previous example follow a flawed analogy to an actual pyramid.
The first example of a funnel chart comes from the FusionCharts Free Chart Gallery.
This example shows the flawed analogy I’ve alluded to, which indicates that some quantity goes from a large number to a small number, starting with website visits, only a fraction of which result in downloads, and only a fraction of those result in inquiries about purchase, etc. It seems to me that a physical funnel should make everything that goes in the top come out the narrower bottom. If it didn’t work that way, your kitchen would become a disaster. [Read more…] about Bad Graphics – Funnel Chart
I’ve decided to follow up to my recent Close Races post. My last chart in that post was a dot plot, and the lines were dark enough to detract from the plotted points (below left). I’ve lightened the lines (below right) to reduce this effect, while keeping the lines to help viewers trace the series. The lighter lines seem to help a bit. I’ve also replaced the teal/cyan (hard to view”) with a plum shade for Clinton.
