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On the Role of Text Preprocessing in BERT Embedding-based DNNs for Classifying Informal Texts

—Due to highly unstructured and noisy data, analyz- ing society reports in written texts is very challenging. Classifying informal text data is still considered a difﬁcult task in natural language processing since the texts could contain abbreviated words, repeating characters, typos, slang, et cetera. Therefore, text preprocessing is commonly performed to remove the noises and make the texts more structured. However, we argued that most tasks of preprocessing are no longer required if suitable word embeddings approach and deep neural network (DNN) ar- chitecture are correctly chosen. This study investigated the effects of text preprocessing in ﬁne-tuning a pre-trained Bidirectional Encoder Representations from Transformers (BERT) model using various DNN architectures such as multilayer perceptron (MLP), long short-term memory (LSTM), bidirectional long-short term memory (Bi-LSTM), convolutional neural network (CNN), and gated recurrent unit (GRU). Various experiments were conducted using numerous learning rates and batch sizes. As a result, text preprocessing had insigniﬁcant effects on most models such as LSTM, Bi-LSTM, and CNN. Moreover, the combination of BERT embeddings and CNN produced the best classiﬁcation performance.