Democratic presidential frontrunner Hillary Clinton's campaign attempted to make an interesting point about gun regulations on Friday. It ended up tweeting out an incredibly poorly designed and ultimately confusing chart.

The chart appears to be based on the idea of a Venn diagram, a very common chart used to illustrate the overlap between two sets. Clinton's campaign seems to be trying to argue that there is a big overlap between gun owners and Americans who support background checks for gun purposes.

Unfortunately, the chart completely fails at the basic elements of being a Venn diagram:

A Venn diagram of this type is useful for illustrating two distinct sets that have some overlap. But in this case, that isn't true — Clinton's two sets are "Americans" and "gun owners."

But she is presumably talking about American gun owners and their support for background checks. That makes the second set a proper subset of the first. As it is, the chart suggests that a large number of gun owners are not Americans.

A better layout might have the first set be "Americans who support background checks." Then, at least, we could be properly looking at the overlap between two sets.

This isn't the first time a prominent Democratic politician has messed up a Venn diagram. In his 2013 State of the Union, President Barack Obama showed a chart comparing US and Chinese investment in solar energy, similarly abusing the Venn diagram format.