Would a 24 percent increase in murders make the news? Not when the victims are police officers.

The 2018 LODD numbers for the first half of the year from the National Law Enforcement Officers Memorial Fund show a 24 percent increase in murders of police officers over the first half of 2017, with 10 percent of the 31 firearms-related deaths coming in the form of ambush.

Despite millions of police-citizen contacts every day, violent encounters are a small percentage of those interactions, and fatalities are statistically exceptionally rare. This makes the significance of line of duty deaths as a predictor of future deaths, or the ability to develop clear cause-effect relationships to help us identify preventive measures, difficult to calculate.