Conclusions
Deep Learning has good performance and promise in many areas, such as natural language processing. Deep Learning has this opportunity to address the data analysis and learning problems in Big Data. In contrast to data mining approaches with its shallow learning process, Deep Learning algorithms transform inputs through more layers. Hidden layers in Deep Learning are generally used to extract features or data representations. Tis hierarchical learning process in Deep Learning provides the opportunity to fnd word semantics and relations. Tese attributes make Deep Learning one of the most desirable models for sentiment analysis.
In this paper, based on our results we show that convolutional neural networks can overcome data mining approach in stock sentiment analysis. In standard data mining approach to text categorization, documents represent as bag-of-word vectors. Tese vectors represent which words appear in a document but do not consider the order of the words in a sentence. It is clear that in some cases, the word order can change the sentiment of a sentence. One remedy to this problem is using bi-grams or n-gram in addition to uni-gram [86, 105, 106]. Unfortunately, using n-grams with n > 1 is not efective [107]. Using CNN provides this opportunity to use n-grams to extract the sentiment of a document efectively. It benefts from the internal structure of data that exists in a document through convolution layers, where each computation unit responds to a small region of input data. We used logistic regression, which works based on a bagof-words, as a baseline and compared the result of applying Deep Learning to logistic regression. Based on our results, among diferent common Deep Learning methods in sentiment analysis, only convolutional neural network outperforms logistic regression. Te accuracy of convolutional neural networks, in comparison to the other models, is considerably better. Based on our results we can use CNN to extract the sentiment of authors regarding stocks from their words. Tere are some people in the fnancial social network who can correctly predict the stock market. By using CNN to predict their sentiment we can predict future market movement.