Rep Paul Ryan is the most ideologically far-from-center vice presidential nominee since at least 1900, according to one statistical analysis of historical Congressional voting records.

Based on the DW-NOMINATE model, Ryan’s record makes him the most extreme nominee from either party during that stretch, meaning he is not only ranked as more conservative than any past GOP vice presidential nominee, but also as further from center than any Democratic number two over that same stretch.

That ranking system analyzes all the roll call votes cast by members of Congress and computes a weighted average of how conservatives or liberal elected representatives are based on those votes. For example, the system pegs Congressional Progressive Caucus co-chair Raul Grijalva (D-NM) as the ninth-most liberal member of the House, while Ron Paul (R-TX) ranks as the second-most conservative member (Rep. Jeff Flake (R-AZ) barely beat out Paul for the title of most conservative.)