Jacob Aasland Ravndal has an interesting piece in the Washington Post laying out some serious obstacles to measuring trends:
Media reporting often resorts to two of the most well-known terrorism databases — the Global Terrorism Database (GTD) and Europol’s annual Terrorism Situation & Trend Report (TE-SAT) — both of which are poorly equipped to capture right-wing terrorism and violence. GTD does not code for the perpetrator’s ideological motivation. Therefore, reports on right-wing attacks based on GTD data, such as the Global Terrorist Index, have to manually browse the data to identify relevant events. In addition, GTD only includes a fraction of right-wing attacks registered in other data sets.
Ravndal argues for a different method: focusing on deadly attacks, which seldom go unreported, and drawing information from the United States Extremist Crime Database (ECDB) and Right-Wing Terrorism and Violence in Western Europe (RTV). Using these sources, he finds that right-wing violence if anything has declined, especially in Europe.
More than anything, the piece illustrates how uncertain this all is, but Ravndal’s approach seems sensible, and at minimum he proves that claims of rising right-wing violence are ill-founded.