No more naked numbers

“When you have mastered numbers, you will in fact no longer be reading numbers, any more than you read words when reading books. You will be reading meanings.” – W. E. B. Du Bois, Afro-American activist and writer

It’s often good to quote numbers in your presentation. They provide powerful means to support the dialog you’re conducting with your audience. But, beware: figures don’t always speak for themselves. In science, naked numbers are numbers without units. Any scientist or economist will tell you that numbers without labels and charts without legends are meaningless and worthless. How would you feel about being offered a salary of “25”, not knowing if you’ll get 25 euros, 25 cents, or 25 peanuts for your work? per hour, per day, or per week?


Also in my job as a strategist and marketer, I’m frequently confronted with naked numbers, industry analyst reports that contradict each other, and quantitative claims that don’t seem to make any sense at all. As Plato, the Greek philosopher, already said 24 centuries ago: a good decision is based on knowledge and not on numbers. This is exactly why you shouldn’t present naked figures, but complement them by the sources and the formulas you used to obtain them.

And still, even the most unprovable forecasts and improbable measurements may yield good presentation material. Not because of their objective value, but just because some people may agree and others will disagree with them. And that’s exactly the sort of conflict you need to create for fueling a conversation with or between your audience. You’ll get an opportunity to discuss the why and the how, explain the logic behind your story, clarify the assumptions you made, bring additional facts and figures, talk about use cases and customer references, and prove the value of your products and services.

Finally, also remember what I wrote in my “living by numbers” post on this blog: numbers, particularly very large ones, don’t resonate with people until they are presented in an appropriate format. So, it remains essential to use good visualization methods for giving meaning to your figures, and making your audience remember the data you quote.

Related posts:

The incredible lightness of numbers

As my day job is in strategic marketing, I often have to deal with numeric data, such as market size, market shares, revenue forecasts, etc. That’s maybe the reason I stopped believing in naked figures. Particularly when presented in isolation, without any information about their source, logic or meaning.

Take this example. A few months ago I was preparing a presentation about disruptive market trends in telecom. While crafting a slide about the massive potential of the Internet of Things, I got confronted with growth forecasts ranging from 26 billion units by 2020 to 212 billion things in 2020.”  Yes, that’s a difference of a factor of almost ten. One would expect a bit more alignment between respected industry analysts like Gartner and IDC. It was even impossible to tell which estimate was the most accurate one, because it wasn’t also very clear what “units” or “things” they actually counted…

Here’s my point: numbers are meaningless without context or without a good explanation. There’s a quote attributed to Winston Churchill, saying that:

“The only statistics you can trust are those you falsified yourself.”

Although sources claim that Sir Winston never made such statement at all – which means that you should be as cautious when citing quotes as when showing numbers – there’s certainly some truth in it:

  • Most presenters use figures either to prove their point or to persuade their audience (of a point they aren’t able to prove.) Both may of course be honorable causes, but still, as a member of the audience this often gives me an uncomfortable feeling of being manipulated.
  • Even when facts and figures are not intentionally misleading, they still may be massaged to invoke more (or less) emotion (see e.g. Garr Reynolds’ example about the usage or tables and charts in my previous post.) And of course, the same numbers can mean different things to different people.
  • You can prove anything you want with numbers, statistics and correlations.  From a 2011 BusinessWeek article I learned that Facebook ignited the Greek debt crisis, and that Global Warming is caused by scientific research… If you (or the people listening to you) have no idea of what’s behind a correlation, you may claim any fact you like.
    Another more recent case of such correlation equals causation thinking – also known as the cum hoc ergo propter hoc fallacy – is a Princeton study saying that Facebook would lose 80% of its users by 2017. The numbers generated a  row between the Princeton University researchers and the Menlo Park social networking giant, as the latter on its turn “proved” that the renowned university would lose all of its students by 2021.


As a conclusion, if you want to include numbers, statistics and correlations in your presentation, use them scarcely, carefully and wisely. Always mention their source(s), present them with the necessary reservation, and in the right context.

For what it’s worth: last week, Google announced a new tool that should help data analysts distinguish cause from correlation, when e.g.measuring sales generated by a web banner, or estimating the impact of a new feature on app downloads.

More reading:

Living by numbers

In a business or technology talk, the audience is too often confronted with slideuments that misuse PowerPoint to present large tables with huge amounts of numerical or statistical data.

Numbers are indeed a powerful tool –sometimes even an essential one– to support your story and prove your statements. But, are you really sure that the folks in the room will understand and remember all the data you present? Numbers don’t resonate with people until they are placed into the right context and displayed in an appropriate format.

Here are a few tips for embedding small data and big data into your presentations:

  • Present only the essential. Select a few compelling facts or crispy figures that support your message. Don’t lose your time –and the audience’s– by reading the numbers out loud. Distribute the bulk data and the nitty-gritty details as a handout (there is a misunderstanding that the hard or soft copies you give away after your presentation always need to contain exactly the same information as the slides you projected on the screen.)

  • Use images and charts instead of digits. The human brain interprets every digit as a picture, so complex tables and calculations literally overload your brain. A good visual representation or an infographic is lighter to digest and will better stick with the public.
    There are zillions of alternatives to bar charts and pies to depict numerical data. If you need inspiration, have a look at this periodic table of visualization methods published by And when you want to add animated charts to your PowerPoints, you might learn to handle data like Hans Rosling.

  • Illustrate your figures with metaphors. (Visual) metaphors help you to capture the audience’s attention and to convey complex concepts. They also let your listeners better grasp the order of magnitude and the importance of the (sometimes transcendental) numbers you may be showing them.

A final word of caution: get your numbers right! People won’t appreciate that you provide them with false facts. Also make sure you know the details behind the numbers and that you can explain or motivate the data you present.

More guidelines and best practices for writing stories about numbers and bringing statistics to life for non-statisticians can be found in the Making Data Meaningful series, published by the United Nations Economic Commission for Europe (UNECE).