There is one really great thing about Microsoft Excel, and one really dangerous thing.

The great thing is that it’s dead easy to create charts. Bar charts, pie charts, histograms, 3D charts, line graphs — you name it, Excel can do it in a second. All you have to do is select the data to be included, and click on a couple of things, and you’re good to go.

The dangerous thing is that it’s dead easy to create charts. Bar charts, pie charts, histograms…. Why dangerous? Because you can easily select the wrong type of graph for the data, or for the purpose you have in mind. It’s easy, in other words, to create graphs and charts that are either inappropriate or, worse, downright misleading.

This is why when you’re teaching kids how to manipulate data in spreadsheets, and how to display the data (a picture paints a thousand words and all that), it’s not enough to point out which buttons to click on. You should also teach them how to make the right choices.

If doing so is outside your comfort zone, this book should help. Subtitled “Getting smarter about visual information”, it takes the reader through the details of how to create good charts, and then gives plenty of examples of how some people have created bad ones.

The first chapter, on how charts work, provides a decent grounding in the theory. It is, to be honest, a bit dry, but it’s worth persevering with.

The rest of the book is more entertaining — not usually a word one might associate with a book on data and graphs, but a good one on this case. The author, Alberto Cairo, makes the subject very interesting, with examples drawn from real life as well as fictitious ones.

We learn that some charts lie simply by being poorly designed — hence my comments about spreadsheets at the beginning of this article. Others, however, lie by displaying dubious data. Sometimes the original data is legit, but is then reworked in such a way as to give a completely misleading impression. And sometimes, this can lead to real-world tragedies when someone takes it upon themselves to act on the (mis)information in the most violent way possible. In such ways, misleading charts are, in effect, another manifestation of fake news.

There are other ways that charts can give false information, including by not providing all of the data required to see the real picture. There’s a reason that courts of law ask witnesses to tell the truth, the whole truth, and nothing but the truth: it’s possible to lie by omission as well as by commission.

Students need to learn how to read charts. One of the big mistakes that was made in my original subject, Economics, was removing a third paper from the ‘A’ Level examination of one particular board. It was a data paper, and students had to interpret a table of data and/or some charts. I heard that the examination board abandoned the idea because candidates found it too difficult. That would suggest to me a good reason to not abandon it, in order to force them to become more data and graphical literate.

Students also need to learn how to create charts that are meaningful and useful rather than just pretty to look at. However, if I were teaching I’d set some work in which students had to adopt a particular position, and then deliberately manipulate the data or its presentation in order to support their argument. I did this kind of thing in my Economics classes, to help students spot deliberately misleading headlines and graphs. Once you’ve seen how a false impression can be created, it’s much easier to see the telltale signs when someone tries the same trick on you.

Although this was of course not the author’s intention, this book provides a how-to guide on creating charts that lie! It’s a good book to read, and definitely one you’ll want in your armoury of resources.

But use it wisely, and with caution!