Tuesday, January 05, 2016

Is Modern Medicine the Reason for the Falling Murder Rate?

One of the most interesting facts in the debate about guns and crime in the United states over the last 20+ years is that the murder rate has fallen in half while the number of guns per capita has increased from .89 in 1993 to 1.18 in 2014, an increase of 33 percent.  One of the thesis that is put forward for the decrease in murder rates is better medical technology.  Clearly, there have been significant improvements in the availability of emergency transport, access to emergency personnel through the ubiquity of cell phones and emergency providers, and better surgical and diagnostic techniques for emergency trauma, such as gunshot wounds.  A commenter at freerepublic.com sums up the argument in a post, claiming that the reduction in murder rates is due to better medical care. From Paal Gulli at freerepublic:
It’s a stupid argument because a “murder” necessarily means someone dies. So any “murder” rate necessarily is greatly influenced by the availability and quality of emergency medical care. Statistically, over the same period as represented in the graph, the survival rate for GSW victims in America has increased faster than the number of murders has decreased, indicating that while more people are being shot, fewer enough are dying that the murder rate is in decline. Hardly brag-worthy.

Point of fact, it’s an inherently deceptive statistic. The use of disinformation and outright lies is the other side’s stock in trade. We need to avoid using those same tools, else we’re no better than they are.
I am interested in the argument, because it has some surface plausibility.  Clearly, emergency care and availability have improved.  But does that mean the murder rate is "greatly influenced" by them?   It may or may not be.  What percent of murder victims had access to emergency care is unknown.  If the victim died before they were picked up by emergency care providers, improved emergency care would not have any effect on those murders. It is not at all clear that improved emergency care would "greatly influence" the murder rate. 

Here is a test of the hypothesis.  If improved medical care was the major cause of the decline in murder rates, then it is expected that the ratio of murders to violent crime would decrease.  Improved emergency care may reduce the murder rate, but it would not reduce the violent crime rate.  It might increase the violent crime rate by increasing the survival rate of criminals, who are the majority of murder victims.  If the violent crime rate remained the same, but the murder rate was reduced, the ratio of murders to violent crime would be reduced.

The FBI tracks violent crime as well as murder rates.  We can easily plot the number of murders per 100 violent crimes.  In the graph above, you can see that the murder per violent crime ratio remains flat from 1993 to 2014.

Over the same period, the murder rate drops precipitously from 1993 to 2000, remains relatively flat through 2007, then drops at a slower rate through 2014.  This FBI source has the numbers for for 2013 and 2014.

I have attempted to determine how many nonfatal gunshot victims there were per year, over the period.  If we knew that we might determine the survival rate.  But details are hard to come by.  From BJS.gov(pdf):
The number of gunshot wounds from assaults treated in hospital emergency departments fell from 64,100 in 1993 to 39,400 in 1997, a 39% decline. Homicides committed with a firearm fell from 18,300 in 1993 to 13,300 in 1997, a 27% decline.
If we believe those numbers, the number of murders declined less than the numbers of people treated for gunshots, which is exactly opposite of what would be expected if the survival rate from gunshots were increasing dramatically.

The gunshot survival rate numbers that I have seen tend to be for specific areas; there do not seem to be any clear numbers for the nation before 2001.  Even those numbers are clouded by the potential for increased reporting as the system was implemented.  Most of the drop in murder rates occurred before that date. 

The bureau of Justice Statistics has a chart covering the period from 1993 to 2011.  It shows a drop in overall non-fatal firearms victimizations that mostly parallels the drop in murder rates, as you would expect. 

But overall non-fatal firearm victimizations are not necessarily gun shots.  Gun shot victims are likely to be only a small percentage of non-fatal firearm victimizations, as most robberies with firearms do not involve the victim being shot.

Another possibility is that the number of justified shootings is increasing.  It is more likely that those shot justifiably would survive, because a justified shooter is more likely to call emergency responders than a murderer is.  The number of concealed carry permit holders is up dramatically over 1993-2014, increasing by about 13 million from around a million in 1993.   Of crimes reported as homicides, it is likely that 10% are justified.  The FBI definition and reporting system grossly under reports justified homicides(pdf).

Murders remain the most reliable of crime statistics.  There is a body.  It is almost always reported.   All other crime statistics tend to have less reliability in reporting and recording.

Is the theory that the major driver of the reduction in murder rates better emergency treatment, especially of gunshots, true?  It seems unlikely to be so, when it just happens that all other violent crime had dropped at almost exactly the same rate as murders, crimes that are not affected by better emergency medical care.

 ©2016 by Dean Weingarten: Permission to share is granted when this notice and link are included.
Link to Gun Watch


Anonymous said...

I did this math. The number of gunshot wounds not resulting in death can be tracked up until 2013 on the CDC site, WISQARS, and you can choose assault related firearms injuries resulting in hospitalization. (What previously killed would definitely result in a stay today, not a treat and release.) That number has been increasing for the past few years running while deaths are falling.


It results in this - however, every single stat barring two has an asterisk which says "Estimation is unstable due to small sample size." But...the trend looks pretty clear. Definitely an overall increase in hospitalization requiring firearm violence related injuries. (Suicide is excluded by the search, it's limited to assault type.)

Year Injuries Population Crude Per Capita Rate

2001 17,925* 284,968,955 6.29
2002 18,440* 287,625,193 6.41
2003 20,424* 290,107,933 7.04
2004 22,109* 292,805,298 7.55
2005 26,732* 295,516,599 9.05
2006 26,348* 298,379,912 8.83
2007 24,233* 301,231,207 8.04
2008 26,938* 304,093,966 8.86
2009 20,574* 306,771,529 6.71
2010 25,479 308,745,538 8.25
2011 27,615* 311,582,564 8.86
2012 31,161 313,873,685 9.93
2013 34,362* 316,128,839 10.87

That being said, if you compare this to violent crime trends from the FBI UCI, you still see a steady downward trend in violent crime overall meaning that even with this shift from fatality to injury, our society is becoming less violent to the point where the difference isn't enough to affect that trendline yet.

Hypnogator said...

A factor which may partially counterbalance the improved medical care may be the improvement in bullet technology over the past decade. Federal HST and similar bullets have much greater wounding capacity than the older JHPs, which translates into greater lethality.

Of course, not all, or even most, shootings involve premium controlled expansion bullets, but those that do may prove more difficult to treat than those that involve FMJs or older expanding bullet designs.

Dean Weingarten said...

Yes, the WISQARS data is there, but only since 2001, which is *after* the major fall in the murder rates. It is very hard to determine how good the WISQARS data is in the early years. I suspect there is some "spin-up" to get people used to the forms and reporting, but it is hard to be certain.

Thanks for the numbers. They may rate an article in themselves. I have used WISQARS before, and it is a fairly user friendly system.

Wireless.Phil said...

That "Legal Intervention" can through your numbers off.

Unknown said...

Obama is hiding a dark secret that just came out and this effects you!

Anonymous said...

2001 is irrelevant. The change in medical care can be seen seen starting in 2012 where you see a continued decrease in deaths and an increase in firearm assault related survivals. It is expected that this trend will continue in 2014 once those figures are compiled. It is the first real anti position that has ever seemed logical or genuine to me, though if you actually still work out the math the rate of injury is so low it seems illogical to worry about it.