Reflecting back on the quick scraping exercise employing the Violence Project’s Mass Shooter Database (detailed in a previous blog post), I was puzzled by one thing.
In thinking through my own mental list of mass shootings which meet the criteria for inclusion with tPP, I was not able to determine why the 2009 shooting at a US Army facility in Forth Hood in Texas was not included. Why was the perpetrator, (then Major) Nidal Hasan, not included in my initial 13 results? 
I decided to investigate. Upon locating the record for Hasan in the Mass Shooter Database, I noticed that he had been excluded from my own scraping approach because his grievance/motive was coded as ‘other’, a category I had decided to exclude. Seeing what to me was such a clearly socio-political crime coded this way got me to think: Are there are crimes in this set, coded as ‘other’ but in fact meeting tPP’s definition of a socio-political motive?
To determine this, I re-ran the same set of procedures: excluding cases prior to 1990, excluding cases where the perpetrator died, then excluding all cases that remained with motives besides those coded as ‘other.’ This left only a 10 cases displayed below:
- Michael Vernon
- Andrew Golden
- Mitchell Johnson
- Emanuel Burl Patterson
- Nidal Hasan
- Riccardo McCray
- William Hudson
- Robert Thomas
- Jarrod Ramos
- Kip Kinkel
From this list, I preformed a cursory investigation into the unknown cases using a news aggregator (i.e. Nexus Uni) and a simple boolean search string (“First name Last Name” AND shooting AND year) which inserted the shooter’s name and the year of the incident. This string returned positive results for all cases, and after reading about the various incidents, none met the criteria for inclusion beyond the attack by Hasan.
In total the Mass Shooter Database provided:
- 23 cases for initial review for possible inclusion
- 14 of these cases met the criteria for secondary investigation and likely inclusion
- 9 of these cases were new to tPP while 5 are used for triangulation and ensuring the reliability of our coding procedures
Although this secondary review did not yield any new results (beyond triangulation information for the Hasan case), it did confirm the thoroughness of the original process and the integrity of the Mass Shooting Database’s conceptual coding. Upon comparing the Mass Shooting Database’s coding of Hasan and tPP’s coding, I found no disagreements in the codes, further cementing the accuracy of both projects’ data.