TPDRC Studies - Subject Categories
| Subject Categories | Number of Studies |
| Terrorism | 197 |
| Terrorist | 131 |
| September 11th | 74 |
| National security | 65 |
| Weapons of mass destruction | 38 |
| Counterterrorism | 29 |
| Nuclear terrorism | 24 |
| Uncategorized | 23 |
| Bombing | 22 |
| Intelligence | 21 |
| World Trade Center | 20 |
| Hate crime | 20 |
| Political violence | 18 |
| Al-Qaeda | 17 |
| Riots | 15 |
| Biological terrorism | 13 |
| Global security | 12 |
| Chemical attack | 12 |
| Homeland security | 11 |
| Anthrax | 10 |
| Ethnic violence | 9 |
| Combating terrorism | 9 |
| Very Small Categories | |
| Terror | 8 |
| Hijacking | 8 |
| Anti-terrorism | 5 |
| Emergency management | 2 |
| Surveillance | 2 |
| Emergency response | 2 |
| Crisis management | 2 |
| Domestic preparedness | 2 |
| Anti-semitic | 1 |
| Aviation security | 1 |
| Bioterrorism | 1 |
| Skyjacking | 1 |
| Information warfare | 1 |
| Organized crime | 1 |
| 37 | |
| Total Subject Categories |
36 |
347 studies: 35 unique subject keyword categories plus 'uncategorized' to account for studies missing subject keywords. 'Very small categories' comprised of subject keyword categories of less than 1%.