Handgun Acquisitions in California After Two Mass Shootings
-- David M. Studdert, LLB, ScD; Yifan Zhang, PhD; Jonathan A. Rodden, PhD; Rob J. Hyndman, PhD; and Garen J. Wintemute, MD, MPH

Background: Mass shootings are common in the United States. They are the most visible form of firearm violence. Their effect on
personal decisions to purchase firearms is not well understood. 

Objective: To determine changes in handgun acquisition patterns after the mass shootings in Newtown, Connecticut, in 2012
and San Bernardino, California, in 2015.

Design: Time-series analysis using seasonal autoregressive integrated moving-average (SARIMA) models.

Setting: California.

Population: Adults who acquired handguns between 2007 and 2016.

Measurements: Excess handgun acquisitions (defined as the difference between actual and expected acquisitions) in the
6-week and 12-week periods after each shooting, overall and within subgroups of acquirers.

Results: In the 6 weeks after the Newtown and San Bernardino shootings, there were 25 705 (95% prediction interval, 17 411 to
32 788) and 27 413 (prediction interval, 15 188 to 37 734) excess acquisitions, respectively, representing increases of 53% (95%
CI, 30% to 80%) and 41% (CI, 19% to 68%) over expected volume.  Large increases in acquisitions occurred among white and
Hispanic persons, but not among black persons, and among persons with no record of having previously acquired a handgun.
After the San Bernardino shootings, acquisition rates increased by 85% among residents of that city and adjacent neighborhoods,
compared with 35% elsewhere in California.

Limitations: The data relate to handguns in 1 state. The statistical analysis cannot establish causality.

Conclusion: Large increases in handgun acquisitions occurred after these 2 mass shootings. The spikes were short-lived and
accounted for less than 10% of annual handgun acquisitions statewide. Further research should examine whether repeated
shocks of this kind lead to substantial increases in the prevalence of firearm ownership.

Primary Funding Source: None.

Ann Intern Med. doi:10.7326/M16-1574 Annals.org
For author affiliations, see end of text.
This article was published at Annals.org on 2 May 2017.

Apparently, the researchers haven't learned the lesson all other firearms statistical reports have taught us --
You can not establish causation, no matter how many times you study something and find data that show some correlation.

They do recommend additional studies, but those will likely need to be funded by the tax payers or Bloomberg's Gun Sense activists.

Probably written by pseudo researchers who can't find a real job 

Probably written by pseudo researchers who can't find a real job 

I'm sure with all those letters after their names, they are extremely objective and scientific at heart!