Georg Groh


2020

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An Evaluation of Progressive Neural Networksfor Transfer Learning in Natural Language Processing
Abdul Moeed | Gerhard Hagerer | Sumit Dugar | Sarthak Gupta | Mainak Ghosh | Hannah Danner | Oliver Mitevski | Andreas Nawroth | Georg Groh
Proceedings of the 12th Language Resources and Evaluation Conference

A major challenge in modern neural networks is the utilization of previous knowledge for new tasks in an effective manner, otherwise known as transfer learning. Fine-tuning, the most widely used method for achieving this, suffers from catastrophic forgetting. The problem is often exacerbated in natural language processing (NLP). In this work, we assess progressive neural networks (PNNs) as an alternative to fine-tuning. The evaluation is based on common NLP tasks such as sequence labeling and text classification. By gauging PNNs across a range of architectures, datasets, and tasks, we observe improvements over the baselines throughout all experiments.

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Evaluation Metrics for Headline Generation Using Deep Pre-Trained Embeddings
Abdul Moeed | Yang An | Gerhard Hagerer | Georg Groh
Proceedings of the 12th Language Resources and Evaluation Conference

With the explosive growth in textual data, it is becoming increasingly important to summarize text automatically. Recently, generative language models have shown promise in abstractive text summarization tasks. Since these models rephrase text and thus use similar but different words as found in the summarized text, existing metrics such as ROUGE that use n-gram overlap may not be optimal. Therefore we evaluate two embedding-based evaluation metrics that are applicable to abstractive summarization: Fr ́echet embedding distance, which has been introduced recently, and angular embedding similarity, which is our proposed metric. To demonstrate the utility of both metrics, we analyze the headline generation capacity of two state-of-the-art language models: GPT-2 and ULMFiT. In particular, our proposed metric shows close relation with human judgments in our experiments and has overall better correlations with them. To provide reproducibility, the source code plus human assessments of our experiments is available on GitHub.

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Impact of Politically Biased Data on Hate Speech Classification
Maximilian Wich | Jan Bauer | Georg Groh
Proceedings of the Fourth Workshop on Online Abuse and Harms

One challenge that social media platforms are facing nowadays is hate speech. Hence, automatic hate speech detection has been increasingly researched in recent years - in particular with the rise of deep learning. A problem of these models is their vulnerability to undesirable bias in training data. We investigate the impact of political bias on hate speech classification by constructing three politically-biased data sets (left-wing, right-wing, politically neutral) and compare the performance of classifiers trained on them. We show that (1) political bias negatively impairs the performance of hate speech classifiers and (2) an explainable machine learning model can help to visualize such bias within the training data. The results show that political bias in training data has an impact on hate speech classification and can become a serious issue.

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Identifying and Measuring Annotator Bias Based on Annotators’ Demographic Characteristics
Hala Al Kuwatly | Maximilian Wich | Georg Groh
Proceedings of the Fourth Workshop on Online Abuse and Harms

Machine learning is recently used to detect hate speech and other forms of abusive language in online platforms. However, a notable weakness of machine learning models is their vulnerability to bias, which can impair their performance and fairness. One type is annotator bias caused by the subjective perception of the annotators. In this work, we investigate annotator bias using classification models trained on data from demographically distinct annotator groups. To do so, we sample balanced subsets of data that are labeled by demographically distinct annotators. We then train classifiers on these subsets, analyze their performances on similarly grouped test sets, and compare them statistically. Our findings show that the proposed approach successfully identifies bias and that demographic features, such as first language, age, and education, correlate with significant performance differences.

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Investigating Annotator Bias with a Graph-Based Approach
Maximilian Wich | Hala Al Kuwatly | Georg Groh
Proceedings of the Fourth Workshop on Online Abuse and Harms

A challenge that many online platforms face is hate speech or any other form of online abuse. To cope with this, hate speech detection systems are developed based on machine learning to reduce manual work for monitoring these platforms. Unfortunately, machine learning is vulnerable to unintended bias in training data, which could have severe consequences, such as a decrease in classification performance or unfair behavior (e.g., discriminating minorities). In the scope of this study, we want to investigate annotator bias — a form of bias that annotators cause due to different knowledge in regards to the task and their subjective perception. Our goal is to identify annotation bias based on similarities in the annotation behavior from annotators. To do so, we build a graph based on the annotations from the different annotators, apply a community detection algorithm to group the annotators, and train for each group classifiers whose performances we compare. By doing so, we are able to identify annotator bias within a data set. The proposed method and collected insights can contribute to developing fairer and more reliable hate speech classification models.

2014

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Estimating Grammar Correctness for a Priori Estimation of Machine Translation Post-Editing Effort
Nicholas H. Kirk | Guchun Zhang | Georg Groh
Proceedings of the EACL 2014 Workshop on Humans and Computer-assisted Translation