Automatically detecting sentiment of product reviews, blogs, tweets, and SMS messages has attracted extensive interest from both the academia and industry. It has a number of applications, including: tracking sentiment towards products, movies, politicians, etc.; improving customer relation models; detecting happiness and well-being; and improving automatic dialogue systems. In this tutorial, we will describe how you can create a state-of-the-art sentiment analysis system, with a focus on social media posts.
We begin with an introduction to sentiment analysis and its various forms: term level, message level, document level, and aspect level. We will describe how sentiment analysis systems are evaluated, especially through recent SemEval shared tasks: Sentiment Analysis of Twitter (SemEval-2013 Task 2, SemEval 2014-Task 9) and Aspect Based Sentiment Analysis (SemEval-2014 Task 4).
We will give an overview of the best sentiment analysis systems at this point of time, including those that are conventional statistical systems as well as those using deep learning approaches. We will describe in detail the NRC-Canada systems, which were the overall best performing systems in all three SemEval competitions listed above. These are simple lexical- and sentiment-lexicon features based systems, which are relatively easy to re-implement.
We will discuss features that had the most impact (those derived from sentiment lexicons and negation handling). We will present how large tweet-specific sentiment lexicons can be automatically generated and evaluated. We will also show how negation impacts sentiment differently depending on whether the scope of the negation is positive or negative. Finally, we will flesh out limitations of current approaches and promising future directions.
Instructors: Saif M. Mohammad, Researcher, National Research Council Canada Saif Mohammad is a Research Officer at the National Research Council Canada. His research interests are in Computational Linguistics, especially Lexical Semantics. He develops computational models for sentiment analysis, emotion detection, semantic distance, and lexical-semantic relations such as word-pair antonymy. Xiaodan Zhu, Researcher, National Research Council Canada Xiaodan Zhu is a Research Officer at the National Research Council Canada. His research interests are in Natural Language Processing, Spoken Language Understanding, and Machine Learning. His recent work focuses on sentiment analysis, emotion detection, speech summarization, and deep learning. The instructors, along with Svetlana Kiritchenko, developed the NRC-Canada Sentiment Analysis System, which was the top-performing system in recent SemEval shared-task competitions (SemEval-2013, Task 2, SemEval-2014 Task 9, and SemEval-2014 Task 4).
Sentiment Analysis of Social Media Texts
Saif M. Mohammad and Xiaodan Zhu
October 25, 2014