Information Liberation 
December 7, 2018
Apparently, it’s just a coincidence that the murder rate is rapidly dropping after President Donald Trump ended Barack Obama’s “War on Cops.”
From The New York Times :
The murder rate in the United States in 2018 is on track for the largest one-year drop in five years.
The numbers obviously aren’t final, and the F.B.I. won’t formally report 2018’s murder figures until September 2019.
But based on a comparison of 2017 data and 2018 data for 66 large American cities (population over 250,000), we can observe the trend as it is occurring and offer a reasonable forecast. (The 2018 data I’ve collected is available here ).
Murder rose 23 percent nationally  between 2014 and 2016 before leveling off  in 2017. Major increases in murder in Chicago  and Baltimore  received much of the national attention, but the increase occurred throughout the country.
In the cities in which data is available, murder has been down about 7 percent on average this year relative to the same point in 2017.
It’s just a coincidence those are the cities where the Black Lives Matter movement had the biggest impact.
If these big cities end the year down about 7 percent from 2017, and if big cities tend to overstate the national trend by about 2.4 percentage points on average, murder should be down by around 4 percent to 5 percent nationally this year.
So far this year, murder in Chicago is down 17 percent in 2018 relative to 2017, accounting for about a third of the drop in the sample. Murder is also down substantially in cities like Baltimore; Charlotte, N.C.; Louisville, Ky.; and Memphis, which all experienced large rises in murder from 2014 to 2016/2017.
According to the Times, the cause for the drop is an eternal mystery:
Tracking the change in murder nationally is far easier than explaining why it’s happening. There is still no consensus on why murder rose nationally in 2015 and 2016, though various theories have been proposed, including simple randomness. Similarly, a projected drop in murder in 2018 would not have an obvious cause. Employment of smarter technologies, expanded community intervention programs, and even colder weather could help explain year-to-year local changes.
No doubt it was “simple randomness!”