Black swans are not predictable but are there fairly rare events that could coour this year in Philadelphia that would skew the homicide rate in an area?
I know of nothing that would cause a sudden drop in the number of homicides in one particular area. Except a mass evacuation. There are a few things that could show up as a sudden rise though.
Terrorist attack. Philadelphia is not a well known terrorist target so any attack there would have to be pretty unpredictable. Terrorist attacks are also very rare so I do not think worth considering in a model.
Going Postal: These seem common enough in America. They have their own list here. I doubt you can predict where they will occur though. Might be worth considering.
Religious nutjobs:The solar temples and the kool aid drinkers in general tend to head off into the sticks before topping each other. So I think there is not much chance of a mass homicide by a cult in
Riots:Cities kick off on a fairly regular basis, The LA riots in 1992 resulted in 53 deaths for example. Philadelphia has had riots in the past. Riots in America seem to be mainly caused by racial tension. It might be possible to if not predict them localise where they are most likely to occur. Then submit a higher homicide count for that area in one of the analytics x prize submissions as an outside bet.
Prisoneers: They love a good ruck. In general prison populations have a higher homicide rate. So looking at changes in prisoner ecosystem in Philadelphia might be worth a look
Natural Disasters:After natural disaster people generally think the world turns into something from a Romero film.
The evidence for this is not that strong for example tales of post Katrina anarchy seem to be overblown. Also natural disasters could reduce the homicide rate as people leave an area after one. Philadelphia is unlikely to undergo a natural disaster though.
There are rare events that still occur often enough to make some sort of prediction on. I do not think any of these is worth including in a model with the possible exception of a riot. But predicting that would need more information about riots and Philadelphia than I have at the moment.