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What is the truncated x-axis trick?

Sometimes numbers are artfully massaged to mislead. Sometimes numbers are blatantly faked. Professor Michael Spagat display here some recent fakes.

Number fakery takes us into scary territory. It’s one thing to learn how to spot a misleading graph that is, nevertheless, based on real numbers, it’s another entirely to pursue numerical claims back to their original sources and find, perhaps, that there’s nothing there.

The truncated x-axis trick

Visit this Padlet, where you’ll find a graph that employs the truncated x-axis trick. This is indeed a trick, but is trivial when compared to a much more serious manipulation; the picture fakes one of the numbers.

The false numbers

The graphic claims that there are more people on “welfare” (or “benefits” in UK parlance) than are working full-time jobs. But the welfare numbers are actually the total number of people living in a household for which at least one person is on welfare, whereas the work numbers are people working full-time jobs themselves, without including the people living in their households.

Further examples of number manipulation

Let’s take another example. US Vice President Mike Pence claimed in 2018 that the US had

“apprehended more than 10 terrorists or suspected terrorists per day at our southern border from countries that are referred to in the lexicon as ‘other than Mexico’ ― that means from the Middle East region.”

However, the Washington Post investigated and found this claim to be false.

The US may stop roughly 10 suspected terrorists per day from entering the US at all ports of entry but it seems that few, if any, of these people try to enter along the southern border.

The two above examples involve false numerical claims emanating from the political right in the USA but the right does not have a monopoly on the circulation of fake numbers. For example, in 2018 a false claim circulated widely that the Trump administration had lost track of nearly 1,500 migrant children, who are all now possible victims of child traffickers.

This claim is based, essentially, on the assumption that not answering a telephone call from US government officials implies that a household’s children have been trafficked.


The three falsehoods outlined above all contain some element of truth, to varying degrees.

How important do you think this truthy element is for the successful propagation of these false stories?

© Royal Holloway, University of London
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Survival Statistics: Secrets for Demystifying Numbers

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