Table 3.

Performance of different sentiment classifiers according to Area under Curve of ROC, accuracy, and F scores for positive and negative sentiment polarity respectively. The baseline system classified all posts as positive.

	AUC of ROC (95% CI)	Accuracy (95% CI)	F (positive) (95% CI)	F (negative) (95% CI)
MaxEnt	82.0% (2.7)	79.4% (1.8)	86.8% (1.9)	53.7% (2.8)
AdaBoost	76.0% (3.3)	76.3% (1.5)	84.6% (2.1)	48.5% (3.9)
SVM	78.1% (2.9)	73.4% (2.9)	68.4% (1.9)	58.4% (1.4)
Baseline	49.8% (0.8)	72.9% (0.7)	84.3% (1.0)	0% (0)