Table 2 Statistics comparing BioCreative II gene normalization task (human) with BioCreative I tasks (mouse, fly, and yeast).

Number of unique IDs

Average synonym length in words

Average synonyms per identifier

Average identifiers per synonym (ambiguity)

BioCreative maximum recall @ precision

BioCreative maximum F-measure

Human

32,975

2.17

5.55

1.12

0.88 @ 0.50

0.81

Mouse

52,494

2.77

2.48

1.02

0.90 @ 0.43

0.79

Yeast

7,928

1.00

1.86

1.01

0.96 @ 0.65

0.92

Fly

27,749

1.47

2.94

1.09

0.84 @ 0.73

0.82