The human element

The job of data visualization is to bridge the gap between the journalist's set of raw information and the reader's understanding of that information. Humans are, by nature, subjective beings, and will impose their own worldview and their own interpretation onto whatever is presented to them. A reader's inherent confirmation bias will make them subconsciously manipulate a graphic in a way that makes it reflect their beliefs or downplay an opposing opinion. Similarly, a graphic can be intentionally made to skew data in a way that communicates something other than the real story.

Misleading graphics are very common in political and religious forums. Intentionally skewed graphics, or even ambiguous graphics shared by thought leaders via social media are widespread, convincing millions of followers that "because the data says so" they must be right.

This graphic circulated democratic media during the presidential race leading up to Trump's 2016 election:



At a glance, this pie chart looks sound. Those are all familiar names. We all know the United States spends big on the military. In fact, every number represented on this chart is true, but paired with the caption, this chart misrepresents the big picture. The above chart only shows discretionary spending, which makes up only ~40% of the overall US budget. A much larger slice of the pie isn't even shown. What's more is that the food stamp program is actually part of the US budget's mandatory spending, which is NOT represented in this chart. A graphic better representing the data is shown below, from Politifact.



This is just a single example, which leaves us with the lesson: always look at a graphic critically, especially in the context of the big picture.