Table 1.

Type of machine learning algorithm used in different level of natural language processing approach. The filled cell indicates the machine learning algorithm used. (ML, machine learning; LASSO, least absolute shrinkage and selection operator; SDT, single decision tree; RF, random forest; SVM, support vector machine; CNN, convolutional neural network; MLP, multilayer perceptron; LSTM, long short-term memory; Bi-LSTM, bidirectional LSTM; CNN-Max, max-pooling CNN; Multi-CNN, multi-kernel CNN).

Type of ML Algorithm		Level of Approach
	Word Level	Sentence Level	Document Level
LASSO regression
SDT
RF
SVM
CNN
MLP
LSTM
Bi-LSTM
CNN&LSTM
CNNmax
Multi-CNN