Among the various locations for "haunted" places (old houses/mansions, graveyards, etc), battlefields rank as fairly common. I suppose the logic being that since lots of humans die in these locations, the likelihood of one or more poor souls turning into ghosts goes up. Likewise, old plantation houses in America, which were home to many slaves, are also fairly common among haunted destinations.
http://en.wikipedia.org/wiki/List_of_reportedly_haunted_locations_in_the_United_States
In the above link, a very high number of the haunted locations come from battlefields, plantations/farms, or other places where high numbers of humans have perished, or were buried.
In regards to the notability of this claim, per wikipedia;
The Battle of Gettysburg was the largest battle in North America. Fittingly, it has many ghost stories.
So, my question is: does an increase in human death in a given specific location increase the frequency of "ghost" reportings later on, relative to the total number of humans living in the area to begin with.