On-ground aircraft accidents and 'gate change'

jbrohan writes: "Last night a fuel truck bumped into an engine of the plane I was booked on to London. It was one of the last flights to leave the airport, it was delayed 30 minutes arriving, it was raining and there was a gate change. Does anyone know how much each of these attributes affect the chances of an on-ground accident. I used to work with obstetrical data and it was informally observed that accidents were associated with three or so bad situations. For example a tired doctor, a snowstorm keeping the consultant away and a fragile mother. My informal impression was that the system could cope with two, but three would sometimes be too much. Air safety people have a good anonymous reporting system and these influences should be detectable."