[inconditus]

Just like how the lack of pirates caused global warming, right? ;) http://en.wikipedia.org/wiki/File%3aPiratesVsTemp_English.jp...

[aw3c2]

That graph makes zero sense. Is the background gradient supposed to be the pirates? Otherwise they are not shown at all. ;)

[DougBTX]

The x axis is number of pirates.

[philh]

To be precise, the x axis is time. It's simply labelled with the number of pirates at that time.

[DougBTX]

It is common to have time on the x-axis, but that doesn't seem to be the case here. The dots on the line are equally spaced horizontally, but the number of years between each dot varies, sometimes it is 20 years, sometimes it is 40 years, so I don't think the horizontal location represents time.

I'd call this a parametric plot, useful when you have two quantities which vary over time, and you want to visualise how they relate to each other. There are some good examples of that on the Ladder of Abstraction demo, http://worrydream.com/LadderOfAbstraction/ The "Abstracting Over Time" graphic is a parametric plot of the position of the car, where x is horizontal position, y is vertical position, and distance along the line is time.

[philh]

Oh, I somehow missed that half of the intervals were only 20 years.

But it's not a parametric plot either, because the number of pirates goes up and then down.

I guess it could plausibly be a normal graph with the X axis being some silly function of time; or a parametric plot with the X axis being a stupid function of pirates. But really I think aw3c2 was right: the graph makes zero sense.

[sesqu]

Here's a better version of the plot: http://i.imgur.com/aXQei.png

This type of plot can be confusing when the relationship isn't strong, but I think it works well enough here.

edit: there's also this plot type: http://i.imgur.com/jgMFS.png

[SimHacker]

It's a parody of religious right wing magical thinking, so it's not supposed to make sense.