make scatter plot start from zero matplotlib

For these types of comparisons, baseline zero is irrelevant.īut a line chart is also often communicating the actual rate of increase/decrease (ie. Or how crime went up faster between November and December than between July and August. For example, a big shift in a stock's price immediately following a major news event. One is the rate of increase/decrease relative to earlier points on the chart. It strikes me that line charts are communicating (at least) two things. We don't want our charts to mislead people, including those who don't look carefully at the axis. While the stakes are (thankfully) not nearly as high when it comes to charts, I think chart creators should also go out of their way to avoid harm. It's an interesting analogy as, when it comes to food allergies, schools, restaurants and stores now go out of their way to alert people to possible allergens, believing their moral duty to prevent harm is greater than just listing 'peanuts' in tiny type on the ingredients list. As David Yanofsky wrote in Quartz:īlaming a chart’s creator for a reader who doesn’t look at clearly labeled axes is like blaming a supermarket for selling someone food he’s allergic to. This is an important point, I think, as people often dismiss concerns about truncated axes (on bar charts or line charts) by arguing a chart is honest as long as the axes are labelled.

So participants were misled even though the axes were properly labelled. It's important to note that, for all the charts used in the 'deceptive' charts study, the actual numbers were visible on the charts (as in the examples above).

As Enrico Bertini, one of the paper's authors notes, the values used in the bar and line charts were not the same, and so we can't really compare them directly to each other.īut this provides at least some evidence that the concerns we have about bar charts - that truncating the y-axis can mislead people - could also apply to line charts.

Make scatter plot start from zero matplotlib