We used 800 topics (w/ lemmatized headwords) tuning on the    5), our SP approach had a smaller (but still statistically significant) absolute F1 gain, with most of the gain coming from core argument type improvements.
the margin of improvement is a modest 0.4 F1 point (on WSJ) over a baseline system with performance over 4 F1 points lower than the top system in CoNLL-2005 (Carreras and Màrquez, 2005).