This week Fairfax reported on Australia’s broadband pricing “war” in an article appearing in both the Sydney Morning Herald and the Age. The publisher thoughtfully spared online readers the egregious chart that it foisted on readers of the paper editions. Judging from this junk (to use the official adjective for low-quality charts), these newspapers should stick to journalism and steer clear of graphics.
The chart in question was brought to my attention by Mule Stable regular @zebra, who also kindly scanned it (and devised the headline of this post), allowing me to reproduce it here. It shows the pricing of a number of broadband internet plans offered by the four largest internet service providers (ISPs) in Australia.
Chart from print edition of The Age (29 April 2010)
It is a busy chart, made difficult to read by a number of ill-advised design decisions:
- the horizontal axis reads from right to left rather than the conventional left to right
- although labeled “Price vs Download”, price is on the horizontal axis, again violating convention*
- repeating the ISP label for every point adds unnecessarily to the busy-ness of the chart and it also makes the legend redundant
- labeling each point with the download limit (although not the price), adds more unnecessary ink
These conventions are arbitrary: we could just as well have developed a tradition in the West of reading from right to left, for example. But once a convention is in place, you have to have a very good reason to break with it. Otherwise, you end up making your chart harder for readers to interpret for no good reason.
But perhaps the biggest weakness in the chart is the labeling of the ISPs. Each has its own colour, but this is not enough for the eye to naturally group them together, which makes it hard to track the pricing trend provider by provider. This is easily addressed by connecting the points for each ISP with lines. Once this is done and the other short-comings are also addressed, a couple of anomalies in the data leap out immediately. Compared to their other plans, the Optus 100GB plan and the TPG 150GB appear dramatically over-priced, costing more than other plans that offer more data.
Of course, this phenomenon was there in the original chart, but it was hidden. So much so, that the journalist does not appear to have noticed at all as it went unremarked in the article. This is a good example of the power of good charting technique.
There are a number of possible explanations for the anomalous data points. They could simply be errors, although it is certainly not impossible (or perhaps even unlikely) that ISPs have illogical pricing policies. A more likely explanation is that the data includes apples and oranges: the higher-priced plans may be bundles offering additional services such as VOIP that are not included in the other more basic plans. Perhaps if Fairfax had done a better job on the chart in the first place, the journalist may have been prompted to answer this question for us.
* Typically “dependent variables” (the y of “y versus x”) appear on the vertical axis and “independent variables” on the horizontal axis.