This applet has a person walking over a street. This is called "a walk".
For each time he crosses the street there is a certain probabaility that he will be hit by a car. This is called "an accident".
The person will cross the street over and over again until he gets fatally hit by a car (i.e if the "Fatal accidents" checkbox is not ticked, the person recouperates after an accident and comes back to walk more), or until he has made it over the street a certain number of times. This is called "a run".
The graph plots on which walk(s) persons gets hit. The walks are grouped in tens. The horizontal axis shows the number of walks. The vertical shows the number of accidents.
The source-code is downloadable as a NetBeans project here.