The effect of pack formation at the 2005 world orienteering   championships
  At the 2005 world championships there was considerable discussion and a formal protest in the long distance race arising from a perceived advantage obtained by some athletes running together. It is shown that a statistical model presented in previous work [1] is applicable to this event, giving predictions of the final times to with 2-3 minutes. Using the model, we show that pack formation was inevitable in this format. The statistical benefit gained at the elite level from running with other competitors appears to derive both from increase speed through the terrain, and the elimination of large navigational errors. 
Graeme J. Ackland