Using probability distributions of convergence / divergence and of rainfall intensity, thresholds were identified and used to classify extreme and background events in each dataset. (osi-saf.org)
There will often be other background events which were also necessary to the injury occurring. (holnesslawgroup.com)
It also allows the designers and developers to trigger background events and camera shifts that give you much greater attachment to the world you're playing in. (thesixthaxis.com)