Table 1.

Evaluation of entity recognition, full gold standard of 18,061 chemical entities. Results of named entity recognition for each assessment and method are shown in this table. The dictionary method recognized a total of 18,683 entities while the machine-learning method recognized 13,832 entities. True positives (TP) is the amount of entity recognitions that agree with the gold standard for each assessment. Values of precision, recall, and F-measure are presented.

Assessment	Method	TP	Precision	Recall	F-measure
Exact matching	Dictionary	5,868	31.41	32.49	31.94
	Machine learning	9,094	65.76	50.35	57.03
Left matching	Dictionary	6,868	36.76	38.03	37.38
	Machine learning	9,892	71.53	54.77	62.04
Right matching	Dictionary	8,015	42.90	44.38	43.63
	Machine learning	10,419	75.34	57.69	65.34
Left/right matching	Dictionary	9,015	48.25	49.91	49.07
	Machine learning	11,217	81.11	62.11	70.35
Partial matching	Dictionary	12,780	68.40	70.76	69.56
	Machine learning	12,328	89.15	68.26	77.32