Table 4.

The performance of applying ML to dataset 1

Models	Feature selection methods	Cross-validation performance				Test performance
		ACC	PRE	REC	F1	ACC	PRE	REC	F1
DT	Unigram	78.04	78.28	78.11	77.78	68.31	68.57	68.31	68.24
	Bi-gram	79.41	79.83	79.09	79.45	69.27	71.06	69.27	69.32
	Tri-gram	72.04	76.49	72.23	70.86	62.34	69.71	62.34	58.74
	Four-gram	67.45	74.49	67.63	65.23	58.44	60.02	58.44	51.28
KNN	Unigram	87.52	88.05	87.52	87.46	80.56	81.42	80.56	80.4
	Bi-gram	86.7	87.34	86.7	86.62	76.06	76.08	76.06	76.05
	Tri-gram	75.84	78.19	75.84	75.33	54.42	76.31	54.42	42.94
	Four-gram	64.83	72.84	64.83	61.55	50.05	65.05	50.05	34.13
LR	Unigram	92.81	92.96	92.81	92.81	89.91	89.93	89.91	89.91
	Bi-gram	90.7	90.94	90.7	90.68	77.27	82.31	77.27	76.43
	Tri-gram	82.51	84.41	82.51	82.13	69.61	76.45	69.61	67.66
	Four-gram	70.48	79.29	70.48	67.8	64.55	75.39	64.55	60.55
RF	Unigram	88.71	89.23	88.79	88.86	81.9	82.62	81.9	81.82
	Bi-gram	83.05	85.81	83.05	82.32	77.96	78.29	77.96	77.92
	Tri-gram	76.39	79.47	76.55	75.97	64.59	65.27	64.59	64.01
	Four-gram	66.92	76.59	67.28	63.15	57.62	74.66	57.62	49.22
SVM	Unigram	92.58	92.71	92.58	92.57	89.57	89.57	89.57	89.57
	Bi-gram	90.5	90.76	90.5	90.48	86.49	86.52	86.49	86.49
	Tri-gram	80.99	83.52	80.99	80.45	74.93	76.42	74.93	74.63
	Four-gram	69.43	79.09	69.43	66.39	60.52	61.11	60.52	60.16
NB	Unigram	90.77	90.92	90.77	90.76	88.57	88.75	88.57	88.55
	Bi-gram	89.6	90.1	89.6	89.55	82.51	83.5	82.51	82.36
	Tri-gram	78.62	82.79	78.62	77.8	63.07	70.95	63.07	58.96
	Four-gram	72.39	79.16	72.39	70.49	58.48	60.61	58.48	50.6