Conservatives (& RKBA & 2A types) looked at the same report and crowed about the decline in murder rates that it showed.
This also is a “logical error” because murder rates are directly linked to the quality of trauma care a shooting victim receives. Because no matter how many times you get shot, if the EMTs and the doctors can keep you alive, there is NO MURDER.
The effectiveness of trauma care always improves over time but especially so in times of war. And the US now has been at war for 18 straight years. Plus large cities and municipalities are spending more on first responder infrastructure to reduce fire and ambulance response times.
So one would expect the “murder” rate to decrease over time for the simple fact that more victims of life-threatening injury of every sort are having their lives saved by improved trauma care.
So from the standpoint of the culpability of firearms, as a stand-alone statistic a decrease in the murder rate is insignificant. You’d have to balance that against other statistics, such as the overall numbers of shootings and firearms assaults, and survival rate among GSW victims before you could begin to know whether it was news worth crowing about.
There are numerous potential variables. Clearly, emergency medical care is one.
It is nearly impossible to correct for all the variables.
The best I have been able to glean is firearms possession and carry has minimal effect on homicide rates.
My suspicion is homicide may be transferred to other targets, softer targets or transformed to justified homicide.
If that is the case, people who are armed would be less likely to be murdered. That simply seems a first order effect to me.