7 The 'algorithms' are only evaluated on pronouns BC BU CH Cl C2  BC  ---60  0  BU  0  --70  0  CH 60  65  -75 75  Cl  -----C2 ---70 -  8 The difference between the 'worst' and the 'best' systems' mean itt performance is about 1%.
the variance o-2 (a measure of robustness of a system) is lowest for Collins' model 1.