ASTC-NSW day 1: Communicating numbers

This week I’m attending the ASTC-NSW 2010 conference in Sydney. These are the notes that I took during a session by Irene Wong. All the credit for the content and ideas goes to Irene. Any mistakes are mine.

Irene Wong presented a session called “Counting on you: communicating numbers”. She talked about working with numbers, and how we can communicate them to our readers. She quoted Hal Varian from Google, who says that the sexy job in the next ten years will be that of the statistician. Irene thinks he is right. “We are on the verge of a lot of publishing of numbers.”

Irene listed the fields that technical writers will need to write about and where numbers will be important: hardware requirements, exchange rates, electrical units, risk, and so on.

Some numbers are exceptionally important. Most numbers are surrounded by terminology and jargon. It’s our challenge to communicate these numbers in whatever way is best for our users.

Good and bad graphs

Irene started by showing us a graph from the New York Times, 6 February 2002, titled “buying as the ship went down”. Few words, good graph, a good summary.

Next she showed a pie chart from Bunnings. The colours in the chart didn’t match the colours in the key. It was hard to read the key, because it had black text on grey background. Worst of all, the category “Other” was the largest.

She showed other examples of misleading or illegible graphs. For example, the scale was not consistent across the graph, or the bling on the graph distracted from or altered the information. She showed how we can be overwhelmed by numbers, if the presentation is wrong. In a surprisingly large proportion of graphs in the banking industry, the information presented is actually incorrect. The errors are caused by graphical mistakes, not intentional errors.

Irene poses the question: Should we say “no chartjunk” as Tufte does, or should we say that some good graphics are useful in drawing the eye?

What about the usability of graphs?

Irene says we don’t know a lot about the usability of graphs. They’re really just taking off. We do need to know what our users will use the graphs for and what information they will draw from them. How will they interpret the information and will it help them to make a decision? Do they have preferences? There is not a lot of research available on this topic.

Irene pointed out that pie charts can be very hard to read, especially if the slices are more or less the same size or there are many segments. Consider replacing a pie chart with a bar chart.

Another problem we have is that people mistrust statistics. We’re up against the belief that statistics lie.

Some tips from Irene

• Remember people’s limitations with numbers, and in particular with percentages. 53% of Australians are innumerate. The big retailers know this. For example, BigW will tell you there’s 10% off and they will also tell you exactly what the new and old prices are.
• Pay attention to the units of measurement. You don’t publish gold statistics in kilograms.
• Watch out for numbers with lots of zeroes or lots of decimal places.
• Beware of axes that don’t start at zero. They may be OK, but pay attention to them.
• Beware of graphs with two Y axes, one on the left and one on the right. Sometimes this is very useful, but check it carefully.
• Be careful when rounding, that you don’t round so much that you lose the value of the numbers, such as the contrasts in a table.
• This is such an exciting area. If you get it right, the opportunities are excellent. Consider that you may need to set standards for your organisation. This is a good opportunity too.

My conclusion

Irene said she is hoping that a couple of us will get really enthusiastic about communicating numbers, and the rest of us will at least gain some useful information from her talk. Well, I certainly did. This was a very interesting window into the world of communicating numbers, from a knowledgable and engaging speaker. Thank you Irene!