Figure 2. The radial distribution function.

The radial distribution function, $g(r)$, is the ratio of the observed distance between children divided by the distance expected by chance. Chance is based the expected distance between children based on their individual location distribution. When $g(r)>1$, children are clustered more closely than expected by chance. The distribution of $g(r)$ was relatively stable over the three observations. Social contact was defined as children being within a radius, $r$, of 1 m, encompassing the peaks of $g(r)$.