Beware the Bell Curve!
Of course, not all evidence will support what you expect. It may contradict your argument -- it may not fit the usual pattern. This is natural. It is your job to be the devil's advocate. Be critical. Like any other data, you must analyze and interpret this "unfriendly" data along with the data that does tend to support your argument. Above all, don't pretend that this data does not exist.
Recognize that some data lies at the extremes of the infamous bell curve. It is widely scattered from the correlation that you've apparently discovered. In any study, data covers a broad spectrum. In many cases, your answer to this minor predicament may simply go something like this, as vague as it sounds... "This bit of data suggests that society was certainly fluid. There were no pigeon holes into which everything perfectly fit. There were variations regionally across space and through time."
The Scarboro Heights Record V12 #1