Looks to me that right from the start the study has a fatal flaw and it's clearly biased.<p>Just looking at their channel selection is clear that they consider extremist only some forms extremism. Particularly those often considered as aligned with right wing politics.<p>From the Ledwich and Zaitsev paper they reference only the "white identitarian", "anti-sjw" and "men rights activism" categories are selected. But there are more categories that could be considered extremist at a glance like "revolutionary" and "anti-whiteness".<p>Other categories in Ledwich and Zaitsev's paper: Conspiracy, Libertarian, Anti-SJW, Social Justice, White Identitarian, Partisan Left, Partisan Right, Anti-theist, Religious Conservative, Socialist (Anti-Capitalist), Revolutionary, Provocateur, MRA (Mens Rights Activist), Missing Link Media, State Funded Channels, Anti-Whiteness. Some channels in other categories could be considered extremist but would require a nuanced analysis.<p>About the other lists or what actual channels they looked into I can't really say because I can't seem to find the actual list they used. If someone has the full list and categories they used please link it.<p>While it could be possible to analyze the behavior of extremism using only right leaning extremism, it is possible that this pattern does not apply to other forms or ideologies.