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1. Improving NLP Model Performance on Small Educational Data Sets Using Self-Augmentation

   Cochran, Keith ; Cohn, Clayton ; Hastings, Peter ( April 2023 , scitepress.org)

   Jovanovic, Jelena ; Chounta, Irene-Angelica ; Uhomoibhi, James ; McLaren, Bruce (Ed.)

   Computer-supported education studies can perform two important roles. They can allow researchers to gather important data about student learning processes, and they can help students learn more efficiently and effectively by providing automatic immediate feedback on what the students have done so far. The evaluation of student work required for both of these roles can be relatively easy in domains like math, where there are clear right answers. When text is involved, however, automated evaluations become more difficult. Natural Language Processing (NLP) can provide quick evaluations of student texts. However, traditional neural network approaches require a large amount of data to train models with enough accuracy to be useful in analyzing student responses. Typically, educational studies collect data but often only in small amounts and with a narrow focus on a particular topic. BERT-based neural network models have revolutionized NLP because they are pre-trained on very large corpora, developing a robust, contextualized understanding of the language. Then they can be “fine-tuned” on a much smaller set of data for a particular task. However, these models still need a certain base level of training data to be reasonably accurate, and that base level can exceed that provided by educational applications, which might contain only a few dozen examples. In other areas of artificial intelligence, such as computer vision, model performance on small data sets has been improved by “data augmentation” — adding scaled and rotated versions of the original images to the training set. This has been attempted on textual data; however, augmenting text is much more difficult than simply scaling or rotating images. The newly generated sentences may not be semantically similar to the original sentence, resulting in an improperly trained model. In this paper, we examine a self-augmentation method that is straightforward and shows great improvements in performance with different BERT-based models in two different languages and on two different tasks that have small data sets. We also identify the limitations of the self-augmentation procedure. 

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2. MathBERT: A Pre-trained Language Model for General NLP Tasks in Mathematics Education

   Shen, Jia Tracy ; Yamashita, Michiharu ; Prihar, Ethan ; Heffernan, Neil ; Wu, Xintao ; Graff, Ben ; Lee, Dongwon ( December 2021 , NeurIPS 2021 Math AI for Education Workshop)

   Since the introduction of the original BERT (i.e., BASE BERT), researchers have developed various customized BERT models with improved performance for specific domains and tasks by exploiting the benefits of transfer learning. Due to the nature of mathematical texts, which often use domain specific vocabulary along with equations and math symbols, we posit that the development of a new BERT model for mathematics would be useful for many mathematical downstream tasks. In this resource paper, we introduce our multi-institutional effort (i.e., two learning platforms and three academic institutions in the US) toward this need: MathBERT, a model created by pre-training the BASE BERT model on a large mathematical corpus ranging from pre-kindergarten (pre-k), to high-school, to college graduate level mathematical content. In addition, we select three general NLP tasks that are often used in mathematics education: prediction of knowledge component, auto-grading open-ended Q&A, and knowledge tracing, to demonstrate the superiority of MathBERT over BASE BERT. Our experiments show that MathBERT outperforms prior best methods by 1.2-22% and BASE BERT by 2-8% on these tasks. In addition, we build a mathematics specific vocabulary ‘mathVocab’ to train with MathBERT. We discover that MathBERT pre-trained with ‘mathVocab’ outperforms MathBERT trained with the BASE BERT vocabulary (i.e., ‘origVocab’). MathBERT is currently being adopted at the participated leaning platforms: Stride, Inc, a commercial educational resource provider, and ASSISTments.org, a free online educational platform. We release MathBERT for public usage at: https://github.com/tbs17/MathBERT. 

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3. Leveraging Symbolic Knowledge Bases for Commonsense Natural Language Inference using Pattern Theory

   https://doi.org/10.1109/TPAMI.2023.3287837  

   Aakur, Sathyanarayanan N. ; Sarkar, Sudeep ( June 2023 , IEEE Transactions on Pattern Analysis and Machine Intelligence)

   The commonsense natural language inference (CNLI) tasks aim to select the most likely follow-up statement to a contextual description of ordinary, everyday events and facts. Current approaches to transfer learning of CNLI models across tasks require many labeled data from the new task. This paper presents a way to reduce this need for additional annotated training data from the new task by leveraging symbolic knowledge bases, such as ConceptNet. We formulate a teacher-student framework for mixed symbolic-neural reasoning, with the large-scale symbolic knowledge base serving as the teacher and a trained CNLI model as the student. This hybrid distillation process involves two steps. The first step is a symbolic reasoning process. Given a collection of unlabeled data, we use an abductive reasoning framework based on Grenander's pattern theory to create weakly labeled data. Pattern theory is an energy-based graphical probabilistic framework for reasoning among random variables with varying dependency structures. In the second step, the weakly labeled data, along with a fraction of the labeled data, is used to transfer-learn the CNLI model into the new task. The goal is to reduce the fraction of labeled data required. We demonstrate the efficacy of our approach by using three publicly available datasets (OpenBookQA, SWAG, and HellaSWAG) and evaluating three CNLI models (BERT, LSTM, and ESIM) that represent different tasks. We show that, on average, we achieve 63% of the top performance of a fully supervised BERT model with no labeled data. With only 1000 labeled samples, we can improve this performance to 72%. Interestingly, without training, the teacher mechanism itself has significant inference power. The pattern theory framework achieves 32.7% accuracy on OpenBookQA, outperforming transformer-based models such as GPT (26.6%), GPT-2 (30.2%), and BERT (27.1%) by a significant margin. We demonstrate that the framework can be generalized to successfully train neural CNLI models using knowledge distillation under unsupervised and semi-supervised learning settings. Our results show that it outperforms all unsupervised and weakly supervised baselines and some early supervised approaches, while offering competitive performance with fully supervised baselines. Additionally, we show that the abductive learning framework can be adapted for other downstream tasks, such as unsupervised semantic textual similarity, unsupervised sentiment classification, and zero-shot text classification, without significant modification to the framework. Finally, user studies show that the generated interpretations enhance its explainability by providing key insights into its reasoning mechanism. 

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4. On the Power of Pre-Trained Text Representations: Models and Applications in Text Mining

   https://doi.org/10.1145/3447548.3470810  

   Meng, Yu ; Huang, Jiaxin ; Zhang, Yu ; Han, Jiawei ( August 2021 , KDD'21:The 27th {ACM} {SIGKDD} Conference on Knowledge Discovery and Data Mining, August 14-18, 2021)

   null (Ed.)

   Recent years have witnessed the enormous success of text representation learning in a wide range of text mining tasks. Earlier word embedding learning approaches represent words as fixed low-dimensional vectors to capture their semantics. The word embeddings so learned are used as the input features of task-specific models. Recently, pre-trained language models (PLMs), which learn universal language representations via pre-training Transformer-based neural models on large-scale text corpora, have revolutionized the natural language processing (NLP) field. Such pre-trained representations encode generic linguistic features that can be transferred to almost any text-related applications. PLMs outperform previous task-specific models in many applications as they only need to be fine-tuned on the target corpus instead of being trained from scratch. In this tutorial, we introduce recent advances in pre-trained text embeddings and language models, as well as their applications to a wide range of text mining tasks. Specifically, we first overview a set of recently developed self-supervised and weakly-supervised text embedding methods and pre-trained language models that serve as the fundamentals for downstream tasks. We then present several new methods based on pre-trained text embeddings and language models for various text mining applications such as topic discovery and text classification. We focus on methods that are weakly-supervised, domain-independent, language-agnostic, effective and scalable for mining and discovering structured knowledge from large-scale text corpora. Finally, we demonstrate with real world datasets how pre-trained text representations help mitigate the human annotation burden and facilitate automatic, accurate and efficient text analyses. 

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5. When BERT meets Bilbo: a learning curve analysis of pretrained language model on disease classification

   https://doi.org/10.1186/s12911-022-01829-2  

   Li, Xuedong ; Yuan, Walter ; Peng, Dezhong ; Mei, Qiaozhu ; Wang, Yue ( April 2022 , BMC Medical Informatics and Decision Making)

   Natural language processing (NLP) tasks in the health domain often deal with limited amount of labeled data due to high annotation costs and naturally rare observations. To compensate for the lack of training data, health NLP researchers often have to leverage knowledge and resources external to a task at hand. Recently, pretrained large-scale language models such as the Bidirectional Encoder Representations from Transformers (BERT) have been proven to be a powerful way of learning rich linguistic knowledge from massive unlabeled text and transferring that knowledge to downstream tasks. However, previous downstream tasks often used training data at such a large scale that is unlikely to obtain in the health domain. In this work, we aim to study whether BERT can still benefit downstream tasks when training data are relatively small in the context of health NLP.

   We conducted a learning curve analysis to study the behavior of BERT and baseline models as training data size increases. We observed the classification performance of these models on two disease diagnosis data sets, where some diseases are naturally rare and have very limited observations (fewer than 2 out of 10,000). The baselines included commonly used text classification models such as sparse and dense bag-of-words models, long short-term memory networks, and their variants that leveraged external knowledge. To obtain learning curves, we incremented the amount of training examples per disease from small to large, and measured the classification performance in macro-averaged$$F_{1}$$$F_1$score.

   On the task of classifying all diseases, the learning curves of BERT were consistently above all baselines, significantly outperforming them across the spectrum of training data sizes. But under extreme situations where only one or two training documents per disease were available, BERT was outperformed by linear classifiers with carefully engineered bag-of-words features.

   As long as the amount of training documents is not extremely few, fine-tuning a pretrained BERT model is a highly effective approach to health NLP tasks like disease classification. However, in extreme cases where each class has only one or two training documents and no more will be available, simple linear models using bag-of-words features shall be considered.

    

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