James Alan Fox, a professor of criminology at Northeastern University, said that while the drop in homicides follows a ­national trend, it is important to look at the long-term pattern and the corrections that usually follow years with dips or surges.

“This is more of a correction than attributable to any one factor,” Fox said.

In the ‘80s, the rate of violent crime dipped, but was followed by a spike in the early ‘90s with crack cocaine fueling much of the violence. The rate dipped in the late ‘90s, then went up from 2000 to 2010. “The spike at the end of the ­decade is more of an aberration than anything else, and now we are going back to where it used to be at the end of the previous decade,” Fox said.