Can someone explain to me why I do not see isolated vertices in this graph? When I was in (Central Europe) high school, I recall that apart from me, there was considerable amount of people not involved in any kind of relationships, and even not counting them, many people used to have partners from other schools. Is it really like this in American high schools, or did the researchers just choose this way of presenting the results?
"many people used to have partners from other schools."
One thing the researchers noted is that they chose a large-ish but relatively isolated community with a single high school that's about an hour from a major city. This means that geography dictates that students are relatively unlikely to date people from other high schools.
I meant the graph linked in the adjacent comment:
http://researchnews.osu.edu/archive/chainspix.htm
The description states that it presents romantic connections, not the sexual ones. However, rereading the article makes me think that they did not take single students into account when creating this graph.
The article said it was in a small town where the second nearest high school would be more than an hour away. Therefore the only 'legal' relationship they could have with people close enough were in Jefferson High School.
