Remember Six Degrees of Separation (and Six Degrees of Kevin Bacon)? Ever heard that you're not just sleeping with someone, you're sleeping with everyone they ever slept with? Well, here's picture of what those relationships look like.
This is an interesting example of how graphics can be used illustrate data. Time Magazine recently had an interesting article, "A Snapshot of Teen Sex." It describes the results of a study of sexual behavior amongst students at an anonymous but real high school in the Midwestern United States in 1995. An accompanying graphic illustrates who had sex with whom. (Besides describing what teens are up to, the really interesting part of the article is the graphic, which isn't included in Time Oneline Edition version. You can find the graphic in Sexual network of high school mapped by researchers, shown below.)
The picture shows who had relations during an 18-month period. It shows a number of small clusters of people who had relations in small groups (such a 63 monogomous pairs), and then one huge ring of 288 students that each had relations with someone else in the cluster. It's difficult to describe, but easy to see in the picture, hence the value of showing statistical data graphically.
This also shows the limits of graphics, and how they can be misleading. The picture hopes to show how an STD can easily spread from one person to many. The problem is, the picture doesn't show time. Those 288 students probably didn't all have sex at the same time. The circle was probably many isolated parts until people between parts connected to make bigger links and finally a full ring. In other words, there was no ring until enough time went by for enough people to have enough sex with enough partners, and that took awhile (although apparently less than 18 months). So to show the potential path of an STD, the links not only need to show encounters, but the order of the encounters.
Many readers probably look at a picture like this and don't think too discerningly about it. They read the article, glance at the picture, and think, "Golly, if any one of those 288 teens has an STD, so will the rest of them." Well, only if the teen with the STD was part of the first couple in the statistical period to hookup, and only if everyone else in the ring became part of the ring when they hookedup, not through later activities of their partners. So the graphic is interesting, and compelling, but can also lead to false assumptions.
Separately, I also like this quote from the article: "Adult sexual networks...usually involve clusters of wanton individuals known to public-health experts as "core transmitters." (Think prostitutes, NBA stars.)" NBA stars? See Wilt Chamberlain.
Oh, and if you really want to be disturbed about how teens are behaving today, see the movie Thirteen. For a lighter take, see Mean Girls.