A Field Guide to Lies: Critical Thinking in the Information Age Read Online Free Page B

researchers are studying brain activations in patients with schizophrenia (SZ). What are HCs? We aren’t told, but from the context—they’re being compared with SZ—we might assume that it means “healthy controls.” Now, there do appear to be differences between the HCs and the SZs, but, hmmm . . . the y-axis has numbers, but . . . the units could be anything! What are we looking at? Scores on a test, levels of brain activations, number of brain regions activated? Number of Jell-O brand pudding cups they’ve eaten, or number of Johnny Depp movies they’ve seen in the last six weeks? (To be fair, the researchers subsequently published their findings in a peer-reviewed journal, and corrected this error after a website pointed out the oversight.)
    In the next example,gross sales of a publishing company are plotted, excluding data from Kickstarter campaigns.

    As in the previous example, but this time with the x-axis, we have numbers but we’re not told what they are. In this case, it’s probably self-evident: We assume that the 2010, 2011, etc., refer to calendar or fiscal years of operation, and the fact that the lines are jagged between the years suggests that the data are being tracked monthly (but without proper labeling we can only assume). The y-axis is completely missing, so we don’t know what is being measured (is it units sold or dollars?), and we don’t know what each horizontal line represents. The graph could be depicting an increase of sales from 50 cents a year to $5 a year, or from 50 million to 500 million units. Not to worry—a helpful narrative accompanied this graph: “It’s been another great year.” I guess we’ll have to take their word for it.
    Truncated Vertical Axis
    A well-designed graph clearly shows you the relevant end points of a continuum. This is especially important if you’re documenting some actual or projected change in a quantity, and you want your readers to draw the right conclusions. If you’re representing crimerate, deaths, births, income, or any quantity that could take on a value of zero, then zero should be the minimum point on your graph. But if your aim is to create panic or outrage, start your y-axis somewhere near the lowest value you’re plotting—this will emphasize the difference you’re trying to highlight, because the eye is drawn to the size of the difference as shown on the graph, and the actual size of the difference is obscured.
    In 2012,Fox News broadcast the following graph to show what would happen if the Bush tax cuts were allowed to expire:

    The graph gives the visual impression that taxes would increase by a large amount: The right-hand bar is six times the height of the left-hand bar. Who wants their taxes to go up by a factor of six? Viewers who are number-phobic, or in a hurry, may not take the time to examine the axis to see that the actual difference is between a tax rate of 35 percent and one of 39.6 percent. That is, if the cuts expire, taxes will only increase 13 percent, not the 600 percent that is pictured (the 4.6 percentage point increase is 13 percent of 35 percent).
    If the y-axis started at zero, the 13 percent would be apparent visually:

    Discontinuity in Vertical or Horizontal Axis
    Imagine a city where crime has been growing at a rate of 5 percent per year for the last ten years. You might graph it this way:

    Nothing wrong with that. But suppose that you’re selling home security systems and so you want to scare people into buying your product. Using all the same data, just create a discontinuity in your x-axis. This will distort the truth and deceive the eye marvelously:

    Here, the visual gives the impression that crime has increased dramatically. But you know better. The discontinuity in the x-axis crams five years’ worth of numbers into the same amount of graphic real estate as was used for two years. No wonder there’s an apparent increase. This is a fundamental flaw in graph making, but because most