At first glance, it looks like gun deaths are on the decline in Florida. But a closer look shows that the y-axis is upside-down, with zero at the top and the maximum value at the bottom. As gun deaths increase, the line slopes downward, violating a well established convention that y-values increase as we move up the page.
However, as Andy Kirk (@visualizingdata) pointed out:
Its just a reverse arrangement to achieve the metaphor of a blood effect. The more red the more deaths. Don't focus on line, focus on colour
— Andy Kirk (@visualisingdata) April 15, 2014
This was indeed the case, as the inspiration was the fantastic visualization of the Iraq death toll.
— Christine Chan (@ChristineHHChan) April 15, 2014
The issue of graphical literacy is incredibly interesting and important. The ability to read and interpret chart types is something we are not trained to do. We ‘get by’ through experience, practice and exposure. Some people find different charts and graphics easier to read and interpret than others so there is rarely a common experience. As designers, our objective has to be to try help overcome any obstacles people might experience in the readability of our representations, either through our design choices or through explanatory annotations.