Sentiment analysis (also known as opinion mining or emotion AI) is the use of natural language processing, text analysis, computational linguistics, and biometrics to systematically identify, extract, quantify, and study affective states and subjective information. Sentiment analysis is widely applied to voice of the customer materials such as reviews and survey responses, online and social media, and healthcare materials for applications that range from marketing to customer service to clinical medicine. With the rise of deep language models, such as RoBERTa, also more difficult data domains can be analyzed, e.g., news texts where authors typically express their opinion/sentiment less explicitly.[1]


The objective and challenges of sentiment analysis can be shown through some simple examples.

Simple cases

More challenging examples


A basic task in sentiment analysis is classifying the polarity of a given text at the document, sentence, or feature/aspect level—whether the expressed opinion in a document, a sentence or an entity feature/aspect is positive, negative, or neutral. Advanced, "beyond polarity" sentiment classification looks, for instance, at emotional states such as enjoyment, anger, disgust, sadness, fear, and surprise.[2]

Precursors to sentimental analysis include the General Inquirer,[3] which provided hints toward quantifying patterns in text and, separately, psychological research that examined a person's psychological state based on analysis of their verbal behavior.[4]

Subsequently, the method described in a patent by Volcani and Fogel,[5] looked specifically at sentiment and identified individual words and phrases in text with respect to different emotional scales. A current system based on their work, called EffectCheck, presents synonyms that can be used to increase or decrease the level of evoked emotion in each scale.

Many other subsequent efforts were less sophisticated, using a mere polar view of sentiment, from positive to negative, such as work by Turney,[6] and Pang[7] who applied different methods for detecting the polarity of product reviews and movie reviews respectively. This work is at the document level. One can also classify a document's polarity on a multi-way scale, which was attempted by Pang[8] and Snyder[9] among others: Pang and Lee[8] expanded the basic task of classifying a movie review as either positive or negative to predict star ratings on either a 3- or a 4-star scale, while Snyder[9] performed an in-depth analysis of restaurant reviews, predicting ratings for various aspects of the given restaurant, such as the food and atmosphere (on a five-star scale).

First steps to bringing together various approaches—learning, lexical, knowledge-based, etc.—were taken in the 2004 AAAI Spring Symposium where linguists, computer scientists, and other interested researchers first aligned interests and proposed shared tasks and benchmark data sets for the systematic computational research on affect, appeal, subjectivity, and sentiment in text.[10]

Even though in most statistical classification methods, the neutral class is ignored under the assumption that neutral texts lie near the boundary of the binary classifier, several researchers suggest that, as in every polarity problem, three categories must be identified. Moreover, it can be proven that specific classifiers such as the Max Entropy[11] and SVMs[12] can benefit from the introduction of a neutral class and improve the overall accuracy of the classification. There are in principle two ways for operating with a neutral class. Either, the algorithm proceeds by first identifying the neutral language, filtering it out and then assessing the rest in terms of positive and negative sentiments, or it builds a three-way classification in one step.[13] This second approach often involves estimating a probability distribution over all categories (e.g. naive Bayes classifiers as implemented by the NLTK). Whether and how to use a neutral class depends on the nature of the data: if the data is clearly clustered into neutral, negative and positive language, it makes sense to filter the neutral language out and focus on the polarity between positive and negative sentiments. If, in contrast, the data are mostly neutral with small deviations towards positive and negative affect, this strategy would make it harder to clearly distinguish between the two poles.

A different method for determining sentiment is the use of a scaling system whereby words commonly associated with having a negative, neutral, or positive sentiment with them are given an associated number on a −10 to +10 scale (most negative up to most positive) or simply from 0 to a positive upper limit such as +4. This makes it possible to adjust the sentiment of a given term relative to its environment (usually on the level of the sentence). When a piece of unstructured text is analyzed using natural language processing, each concept in the specified environment is given a score based on the way sentiment words relate to the concept and its associated score.[14][15][16] This allows movement to a more sophisticated understanding of sentiment, because it is now possible to adjust the sentiment value of a concept relative to modifications that may surround it. Words, for example, that intensify, relax or negate the sentiment expressed by the concept can affect its score. Alternatively, texts can be given a positive and negative sentiment strength score if the goal is to determine the sentiment in a text rather than the overall polarity and strength of the text.[17]

There are various other types of sentiment analysis, such as aspect-based sentiment analysis, grading sentiment analysis (positive, negative, neutral), multilingual sentiment analysis and detection of emotions.

Subjectivity/objectivity identification

This task is commonly defined as classifying a given text (usually a sentence) into one of two classes: objective or subjective.[18] This problem can sometimes be more difficult than polarity classification.[19] The subjectivity of words and phrases may depend on their context and an objective document may contain subjective sentences (e.g., a news article quoting people's opinions). Moreover, as mentioned by Su,[20] results are largely dependent on the definition of subjectivity used when annotating texts. However, Pang[21] showed that removing objective sentences from a document before classifying its polarity helped improve performance.

Subjective and objective identification, emerging subtasks of sentiment analysis to use syntactic, semantic features, and machine learning knowledge to identify if a sentence or document contains facts or opinions. Awareness of recognizing factual and opinions is not recent, having possibly first presented by Carbonell at Yale University in 1979.[clarify]

The term objective refers to the incident carrying factual information.[22]

The term subjective describes the incident contains non-factual information in various forms, such as personal opinions, judgment, and predictions, also known as 'private states'.[23] In the example down below, it reflects a private states 'We Americans'. Moreover, the target entity commented by the opinions can take several forms from tangible product to intangible topic matters stated in Liu (2010).[24] Furthermore, three types of attitudes were observed by Liu (2010), 1) positive opinions, 2) neutral opinions, and 3) negative opinions.[24]

This analysis is a classification problem.[25]

Each class's collections of words or phrase indicators are defined for to locate desirable patterns on unannotated text. For subjective expression, a different word list has been created. Lists of subjective indicators in words or phrases have been developed by multiple researchers in the linguist and natural language processing field states in Riloff et al. (2003).[26] A dictionary of extraction rules has to be created for measuring given expressions. Over the years, in subjective detection, the features extraction progression from curating features by hand to automated features learning. At the moment, automated learning methods can further separate into supervised and unsupervised machine learning. Patterns extraction with machine learning process annotated and unannotated text have been explored extensively by academic researchers.

However, researchers recognized several challenges in developing fixed sets of rules for expressions respectably. Much of the challenges in rule development stems from the nature of textual information. Six challenges have been recognized by several researchers: 1) metaphorical expressions, 2) discrepancies in writings, 3) context-sensitive, 4) represented words with fewer usages, 5) time-sensitive, and 6) ever-growing volume.

  1. Metaphorical expressions. The text contains metaphoric expression may impact on the performance on the extraction.[27] Besides, metaphors take in different forms, which may have been contributed to the increase in detection.
  2. Discrepancies in writings. For the text obtained from the Internet, the discrepancies in the writing style of targeted text data involve distinct writing genres and styles.
  3. Context-sensitive. Classification may vary based on the subjectiveness or objectiveness of previous and following sentences.[25]
  4. Time-sensitive attribute. The task is challenged by some textual data's time-sensitive attribute. If a group of researchers wants to confirm a piece of fact in the news, they need a longer time for cross-validation, than the news becomes outdated.
  5. Cue words with fewer usages.
  6. Ever-growing volume. The task is also challenged by the sheer volume of textual data. The textual data's ever-growing nature makes the task overwhelmingly difficult for the researchers to complete the task on time.

Previously, the research mainly focused on document level classification. However, classifying a document level suffers less accuracy, as an article may have diverse types of expressions involved. Researching evidence suggests a set of news articles that are expected to dominate by the objective expression, whereas the results show that it consisted of over 40% of subjective expression.[22]

To overcome those challenges, researchers conclude that classifier efficacy depends on the precisions of patterns learner. And the learner feeds with large volumes of annotated training data outperformed those trained on less comprehensive subjective features. However, one of the main obstacles to executing this type of work is to generate a big dataset of annotated sentences manually. The manual annotation method has been less favored than automatic learning for three reasons:

  1. Variations in comprehensions. In the manual annotation task, disagreement of whether one instance is subjective or objective may occur among annotators because of languages' ambiguity.
  2. Human errors. Manual annotation task is a meticulous assignment, it require intense concentration to finish.
  3. Time-consuming. Manual annotation task is an assiduous work. Riloff (1996) show that a 160 texts cost 8 hours for one annotator to finish.[28]

All these mentioned reasons can impact on the efficiency and effectiveness of subjective and objective classification. Accordingly, two bootstrapping methods were designed to learning linguistic patterns from unannotated text data. Both methods are starting with a handful of seed words and unannotated textual data.

  1. Meta-Bootstrapping by Riloff and Jones in 1999.[29] Level One: Generate extraction patterns based on the pre-defined rules and the extracted patterns by the number of seed words each pattern holds. Level Two: Top 5 words will be marked and add to the dictionary. Repeat.
  2. Basilisk (Bootstrapping Approach to Semantic Lexicon Induction using Semantic Knowledge) by Thelen and Riloff.[30] Step One: Generate extraction patterns. Step Two: Move best patterns from Pattern Pool to Candidate Word Pool. Step Three: Top 10 words will be marked and add to the dictionary. Repeat.

Overall, these algorithms highlight the need for automatic pattern recognition and extraction in subjective and objective task.

Subjective and object classifier can enhance the several applications of natural language processing. One of the classifier's primary benefits is that it popularized the practice of data-driven decision-making processes in various industries. According to Liu, the applications of subjective and objective identification have been implemented in business, advertising, sports, and social science.[31]


It refers to determining the opinions or sentiments expressed on different features or aspects of entities, e.g., of a cell phone, a digital camera, or a bank.[35] A feature or aspect is an attribute or component of an entity, e.g., the screen of a cell phone, the service for a restaurant, or the picture quality of a camera. The advantage of feature-based sentiment analysis is the possibility to capture nuances about objects of interest. Different features can generate different sentiment responses, for example a hotel can have a convenient location, but mediocre food.[36] This problem involves several sub-problems, e.g., identifying relevant entities, extracting their features/aspects, and determining whether an opinion expressed on each feature/aspect is positive, negative or neutral.[37] The automatic identification of features can be performed with syntactic methods, with topic modeling,[38][39] or with deep learning.[40][41] More detailed discussions about this level of sentiment analysis can be found in Liu's work.[24]

Intensity ranking

Emotions and sentiments are subjective in nature. The degree of emotions/sentiments expressed in a given text at the document, sentence, or feature/aspect level—to what degree of intensity is expressed in the opinion of a document, a sentence or an entity differs on a case-to-case basis.[42] However, predicting only the emotion and sentiment does not always convey complete information. The degree or level of emotions and sentiments often plays a crucial role in understanding the exact feeling within a single class (e.g., 'good' versus 'awesome'). Some methods leverage a stacked ensemble method[43] for predicting intensity for emotion and sentiment by combining the outputs obtained and using deep learning models based on convolutional neural networks,[44] long short-term memory networks and gated recurrent units.[45]

Methods and features

Existing approaches to sentiment analysis can be grouped into three main categories: knowledge-based techniques, statistical methods, and hybrid approaches.[46] Knowledge-based techniques classify text by affect categories based on the presence of unambiguous affect words such as happy, sad, afraid, and bored.[47] Some knowledge bases not only list obvious affect words, but also assign arbitrary words a probable "affinity" to particular emotions.[48] Statistical methods leverage elements from machine learning such as latent semantic analysis, support vector machines, "bag of words", "Pointwise Mutual Information" for Semantic Orientation,[6] semantic space models or word embedding models,[49] and deep learning. More sophisticated methods try to detect the holder of a sentiment (i.e., the person who maintains that affective state) and the target (i.e., the entity about which the affect is felt).[50] To mine the opinion in context and get the feature about which the speaker has opined, the grammatical relationships of words are used. Grammatical dependency relations are obtained by deep parsing of the text.[51] Hybrid approaches leverage both machine learning and elements from knowledge representation such as ontologies and semantic networks in order to detect semantics that are expressed in a subtle manner, e.g., through the analysis of concepts that do not explicitly convey relevant information, but which are implicitly linked to other concepts that do so.[52]

Open source software tools as well as range of free and paid sentiment analysis tools deploy machine learning, statistics, and natural language processing techniques to automate sentiment analysis on large collections of texts, including web pages, online news, internet discussion groups, online reviews, web blogs, and social media.[53] Knowledge-based systems, on the other hand, make use of publicly available resources, to extract the semantic and affective information associated with natural language concepts. The system can help perform affective commonsense reasoning.[54] Sentiment analysis can also be performed on visual content, i.e., images and videos (see Multimodal sentiment analysis). One of the first approaches in this direction is SentiBank[55] utilizing an adjective noun pair representation of visual content. In addition, the vast majority of sentiment classification approaches rely on the bag-of-words model, which disregards context, grammar and even word order. Approaches that analyses the sentiment based on how words compose the meaning of longer phrases have shown better result,[56] but they incur an additional annotation overhead.

A human analysis component is required in sentiment analysis, as automated systems are not able to analyze historical tendencies of the individual commenter, or the platform and are often classified incorrectly in their expressed sentiment. Automation impacts approximately 23% of comments that are correctly classified by humans.[57] However, humans often disagree, and it is argued that the inter-human agreement provides an upper bound that automated sentiment classifiers can eventually reach.[58]


The accuracy of a sentiment analysis system is, in principle, how well it agrees with human judgments. This is usually measured by variant measures based on precision and recall over the two target categories of negative and positive texts. However, according to research human raters typically only agree about 80%[59] of the time (see Inter-rater reliability). Thus, a program that achieves 70% accuracy in classifying sentiment is doing nearly as well as humans, even though such accuracy may not sound impressive. If a program were "right" 100% of the time, humans would still disagree with it about 20% of the time, since they disagree that much about any answer.[citation needed]

On the other hand, computer systems will make very different errors than human assessors, and thus the figures are not entirely comparable. For instance, a computer system will have trouble with negations, exaggerations, jokes, or sarcasm, which typically are easy to handle for a human reader: some errors a computer system makes will seem overly naive to a human. In general, the utility for practical commercial tasks of sentiment analysis as it is defined in academic research has been called into question, mostly since the simple one-dimensional model of sentiment from negative to positive yields rather little actionable information for a client worrying about the effect of public discourse on e.g. brand or corporate reputation.[60][61][62]

To better fit market needs, evaluation of sentiment analysis has moved to more task-based measures, formulated together with representatives from PR agencies and market research professionals. The focus in e.g. the RepLab evaluation data set is less on the content of the text under consideration and more on the effect of the text in question on brand reputation.[63][64][65]

Because evaluation of sentiment analysis is becoming more and more task based, each implementation needs a separate training model to get a more accurate representation of sentiment for a given data set.

Web 2.0

See also: Reputation management, web 2.0, and web mining

The rise of social media such as blogs and social networks has fueled interest in sentiment analysis. With the proliferation of reviews, ratings, recommendations and other forms of online expression, online opinion has turned into a kind of virtual currency for businesses looking to market their products, identify new opportunities and manage their reputations. As businesses look to automate the process of filtering out the noise, understanding the conversations, identifying the relevant content and actioning it appropriately, many are now looking to the field of sentiment analysis.[66] Further complicating the matter, is the rise of anonymous social media platforms such as 4chan and Reddit.[67] If web 2.0 was all about democratizing publishing, then the next stage of the web may well be based on democratizing data mining of all the content that is getting published.[68]

One step towards this aim is accomplished in research. Several research teams in universities around the world currently focus on understanding the dynamics of sentiment in e-communities through sentiment analysis.[69] The CyberEmotions project, for instance, recently identified the role of negative emotions in driving social networks discussions.[70]

The problem is that most sentiment analysis algorithms use simple terms to express sentiment about a product or service. However, cultural factors, linguistic nuances, and differing contexts make it extremely difficult to turn a string of written text into a simple pro or con sentiment.[66] The fact that humans often disagree on the sentiment of text illustrates how big a task it is for computers to get this right. The shorter the string of text, the harder it becomes.

Even though short text strings might be a problem, sentiment analysis within microblogging has shown that Twitter can be seen as a valid online indicator of political sentiment. Tweets' political sentiment demonstrates close correspondence to parties' and politicians' political positions, indicating that the content of Twitter messages plausibly reflects the offline political landscape.[71] Furthermore, sentiment analysis on Twitter has also been shown to capture the public mood behind human reproduction cycles globally,[72] as well as other problems of public-health relevance such as adverse drug reactions.[73]

While sentiment analysis has been popular for domains where authors express their opinion rather explicitly ("the movie is awesome"), such as social media and product reviews, only recently robust methods were devised for other domains where sentiment is strongly implicit or indirect. For example, in news articles - mostly due to the expected journalistic objectivity - journalists often describe actions or events rather than directly stating the polarity of a piece of information. Earlier approaches using dictionaries or shallow machine learning features were unable to catch the "meaning between the lines", but recently researchers have proposed a deep learning based approach and dataset that is able to analyze sentiment in news articles.[1]

Application in recommender systems

See also: Recommender system

For a recommender system, sentiment analysis has been proven to be a valuable technique. A recommender system aims to predict the preference for an item of a target user. Mainstream recommender systems work on explicit data set. For example, collaborative filtering works on the rating matrix, and content-based filtering works on the meta-data of the items.

In many social networking services or e-commerce websites, users can provide text review, comment or feedback to the items. These user-generated text provide a rich source of user's sentiment opinions about numerous products and items. Potentially, for an item, such text can reveal both the related feature/aspects of the item and the users' sentiments on each feature.[74] The item's feature/aspects described in the text play the same role with the meta-data in content-based filtering, but the former are more valuable for the recommender system. Since these features are broadly mentioned by users in their reviews, they can be seen as the most crucial features that can significantly influence the user's experience on the item, while the meta-data of the item (usually provided by the producers instead of consumers) may ignore features that are concerned by the users. For different items with common features, a user may give different sentiments. Also, a feature of the same item may receive different sentiments from different users. Users' sentiments on the features can be regarded as a multi-dimensional rating score, reflecting their preference on the items.

Based on the feature/aspects and the sentiments extracted from the user-generated text, a hybrid recommender system can be constructed.[75] There are two types of motivation to recommend a candidate item to a user. The first motivation is the candidate item have numerous common features with the user's preferred items,[76] while the second motivation is that the candidate item receives a high sentiment on its features. For a preferred item, it is reasonable to believe that items with the same features will have a similar function or utility. So, these items will also likely to be preferred by the user. On the other hand, for a shared feature of two candidate items, other users may give positive sentiment to one of them while giving negative sentiment to another. Clearly, the high evaluated item should be recommended to the user. Based on these two motivations, a combination ranking score of similarity and sentiment rating can be constructed for each candidate item.[75]

Except for the difficulty of the sentiment analysis itself, applying sentiment analysis on reviews or feedback also faces the challenge of spam and biased reviews. One direction of work is focused on evaluating the helpfulness of each review.[77] Review or feedback poorly written is hardly helpful for recommender system. Besides, a review can be designed to hinder sales of a target product, thus be harmful to the recommender system even it is well written.

Researchers also found that long and short forms of user-generated text should be treated differently. An interesting result shows that short-form reviews are sometimes more helpful than long-form,[78] because it is easier to filter out the noise in a short-form text. For the long-form text, the growing length of the text does not always bring a proportionate increase in the number of features or sentiments in the text.

Lamba & Madhusudhan[79] introduce a nascent way to cater the information needs of today's library users by repackaging the results from sentiment analysis of social media platforms like Twitter and provide it as a consolidated time-based service in different formats. Further, they propose a new way of conducting marketing in libraries using social media mining and sentiment analysis.

See also


  1. ^ a b Hamborg, Felix; Donnay, Karsten (2021). "NewsMTSC: A Dataset for (Multi-)Target-dependent Sentiment Classification in Political News Articles". "Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume"
  2. ^ Vong Anh Ho, Duong Huynh-Cong Nguyen, Danh Hoang Nguyen, Linh Thi-Van Pham, Duc-Vu Nguyen, Kiet Van Nguyen, Ngan Luu-Thuy Nguyen. "Emotion Recognition for Vietnamese Social Media Text". In Proceedings of the 2019 International Conference of the Pacific Association for Computational Linguistics (PACLING 2019), Hanoi, Vietnam (2019).
  3. ^ Stone, Philip J., Dexter C. Dunphy, and Marshall S. Smith. "The general inquirer: A computer approach to content analysis." MIT Press, Cambridge, MA (1966).
  4. ^ Gottschalk, Louis August, and Goldine C. Gleser. The measurement of psychological states through the content analysis of verbal behavior. Univ of California Press, 1969.
  5. ^ USA Issued 7,136,877, Volcani, Yanon; & Fogel, David B., "System and method for determining and controlling the impact of text", published June 28, 2001 
  6. ^ a b Turney, Peter (2002). "Thumbs Up or Thumbs Down? Semantic Orientation Applied to Unsupervised Classification of Reviews". Proceedings of the Association for Computational Linguistics. pp. 417–424. arXiv:cs.LG/0212032.
  7. ^ Pang, Bo; Lee, Lillian; Vaithyanathan, Shivakumar (2002). "Thumbs up? Sentiment Classification using Machine Learning Techniques". Proceedings of the Conference on Empirical Methods in Natural Language Processing (EMNLP). pp. 79–86.
  8. ^ a b Pang, Bo; Lee, Lillian (2005). "Seeing stars: Exploiting class relationships for sentiment categorization with respect to rating scales". Proceedings of the Association for Computational Linguistics (ACL). pp. 115–124.
  9. ^ a b Snyder, Benjamin; Barzilay, Regina (2007). "Multiple Aspect Ranking using the Good Grief Algorithm". Proceedings of the Joint Human Language Technology/North American Chapter of the ACL Conference (HLT-NAACL). pp. 300–307. Archived from the original on August 6, 2016. Retrieved June 16, 2009.
  10. ^ Qu, Yan, James Shanahan, and Janyce Wiebe. "Exploring attitude and affect in text: Theories and applications." In AAAI Spring Symposium, Technical report SS-04-07. AAAI Press, Menlo Park, CA. 2004.
  11. ^ Vryniotis, Vasilis (2013). The importance of Neutral Class in Sentiment Analysis.
  12. ^ Koppel, Moshe; Schler, Jonathan (2006). "The Importance of Neutral Examples for Learning Sentiment". Computational Intelligence 22. pp. 100–109. CiteSeerX
  13. ^ Ribeiro, Filipe Nunes; Araujo, Matheus (2010). "A Benchmark Comparison of State-of-the-Practice Sentiment Analysis Methods". Transactions on Embedded Computing Systems. 9 (4).
  14. ^ Taboada, Maite; Brooke, Julian (2011). "Lexicon-based methods for sentiment analysis". Computational Linguistics. 37 (2): 272–274. CiteSeerX doi:10.1162/coli_a_00049. S2CID 3181362.
  15. ^ Augustyniak, Łukasz; Szymański, Piotr; Kajdanowicz, Tomasz; Tuligłowicz, Włodzimierz (December 25, 2015). "Comprehensive Study on Lexicon-based Ensemble Classification Sentiment Analysis". Entropy. 18 (1): 4. Bibcode:2015Entrp..18....4A. doi:10.3390/e18010004.
  16. ^ Mehmood, Yasir; Balakrishnan, Vimala (January 1, 2020). "An enhanced lexicon-based approach for sentiment analysis: a case study on illegal immigration". Online Information Review. 44 (5): 1097–1117. doi:10.1108/OIR-10-2018-0295. ISSN 1468-4527. S2CID 221766042.
  17. ^ Thelwall, Mike; Buckley, Kevan; Paltoglou, Georgios; Cai, Di; Kappas, Arvid (2010). "Sentiment strength detection in short informal text". Journal of the American Society for Information Science and Technology. 61 (12): 2544–2558. CiteSeerX doi:10.1002/asi.21416.
  18. ^ Pang, Bo; Lee, Lillian (2008). "4.1.2 Subjectivity Detection and Opinion Identification". Opinion Mining and Sentiment Analysis. Now Publishers Inc.
  19. ^ Mihalcea, Rada; Banea, Carmen; Wiebe, Janyce (2007). "Learning Multilingual Subjective Language via Cross-Lingual Projections" (PDF). Proceedings of the Association for Computational Linguistics (ACL). pp. 976–983. Archived from the original (PDF) on July 8, 2010.
  20. ^ Su, Fangzhong; Markert, Katja (2008). "From Words to Senses: a Case Study in Subjectivity Recognition" (PDF). Proceedings of Coling 2008, Manchester, UK.
  21. ^ Pang, Bo; Lee, Lillian (2004). "A Sentimental Education: Sentiment Analysis Using Subjectivity Summarization Based on Minimum Cuts". Proceedings of the Association for Computational Linguistics (ACL). pp. 271–278.
  22. ^ a b Wiebe, Janyce; Riloff, Ellen (2005). "Creating Subjective and Objective Sentence Classifiers from Unannotated Texts". In Gelbukh, Alexander (ed.). Computational Linguistics and Intelligent Text Processing. Lecture Notes in Computer Science. Vol. 3406. Berlin, Heidelberg: Springer. pp. 486–497. doi:10.1007/978-3-540-30586-6_53. ISBN 978-3-540-30586-6.
  23. ^ Quirk, Randolph; Greenbaum, Sidney; Geoffrey, Leech; Jan, Svartvik (1985). A Comprehensive Grammar of the English Language (General Grammar). Longman. pp. 175–239. ISBN 1933108312.
  24. ^ a b c Liu, Bing (2010). "Sentiment Analysis and Subjectivity" (PDF). In Indurkhya, N.; Damerau, F. J. (eds.). Handbook of Natural Language Processing (Second ed.).
  25. ^ a b Pang, Bo; Lee, Lillian (July 6, 2008). "Opinion Mining and Sentiment Analysis". Foundations and Trends in Information Retrieval. 2 (1–2): 1–135. doi:10.1561/1500000011. ISSN 1554-0669. S2CID 207178694.
  26. ^ Riloff, Ellen; Wiebe, Janyce (July 11, 2003). "Learning extraction patterns for subjective expressions". Proceedings of the 2003 conference on Empirical methods in natural language processing -. EMNLP '03. Vol. 10. USA: Association for Computational Linguistics. pp. 105–112. doi:10.3115/1119355.1119369. S2CID 6541910.
  27. ^ Wiebe, Janyce; Riloff, Ellen (July 2011). "Finding Mutual Benefit between Subjectivity Analysis and Information Extraction". IEEE Transactions on Affective Computing. 2 (4): 175–191. doi:10.1109/T-AFFC.2011.19. ISSN 1949-3045. S2CID 16820846.
  28. ^ Riloff, Ellen (August 1, 1996). "An empirical study of automated dictionary construction for information extraction in three domains". Artificial Intelligence. 85 (1): 101–134. doi:10.1016/0004-3702(95)00123-9. ISSN 0004-3702.
  29. ^ Riloff, Ellen; Jones, Rosie (July 1999). "Learning dictionaries for information extraction by multi-level bootstrapping" (PDF). AAAI '99/IAAI '99: Proceedings of the Sixteenth National Conference on Artificial Intelligence and the Eleventh Innovative Applications of Artificial Intelligence Conference Innovative Applications of Artificial Intelligence: 474–479.
  30. ^ Thelen, Michael; Riloff, Ellen (July 6, 2002). "A bootstrapping method for learning semantic lexicons using extraction pattern contexts". Proceedings of the ACL-02 conference on Empirical methods in natural language processing - EMNLP '02. Vol. 10. USA: Association for Computational Linguistics. pp. 214–221. doi:10.3115/1118693.1118721. S2CID 137155. ((cite book)): |journal= ignored (help)
  31. ^ Liu, Bing (May 23, 2012). "Sentiment Analysis and Opinion Mining". Synthesis Lectures on Human Language Technologies. 5 (1): 1–167. doi:10.2200/S00416ED1V01Y201204HLT016. ISSN 1947-4040. S2CID 38022159. Archived from the original on May 10, 2021. Retrieved December 9, 2020.
  32. ^ Deng, Shangkun; Mitsubuchi, Takashi; Shioda, Kei; Shimada, Tatsuro; Sakurai, Akito (December 2011). "Combining Technical Analysis with Sentiment Analysis for Stock Price Prediction". 2011 IEEE Ninth International Conference on Dependable, Autonomic and Secure Computing. IEEE. pp. 800–807. doi:10.1109/dasc.2011.138. ISBN 978-1-4673-0006-3. S2CID 15262023.
  33. ^ Nguyen, Kiet Van; Nguyen, Vu Duc; Nguyen, Phu X.V.; Truong, Tham T.H.; Nguyen, Ngan L-T. (October 1, 2018). "UIT-VSFC: Vietnamese Students' Feedback Corpus for Sentiment Analysis". 2018 10th International Conference on Knowledge and Systems Engineering (KSE). Vietnam: IEEE. pp. 19–24. doi:10.1109/KSE.2018.8573337. ISBN 978-1-5386-6113-0. S2CID 56172224.
  34. ^ Yu, Hong; Hatzivassiloglou, Vasileios (July 11, 2003). "Towards answering opinion questions". Proceedings of the 2003 conference on Empirical methods in natural language processing -. EMNLP '03. Vol. 10. USA: Association for Computational Linguistics. pp. 129–136. doi:10.3115/1119355.1119372.
  35. ^ Hu, Minqing; Liu, Bing (2004). "Mining and Summarizing Customer Reviews". Proceedings of KDD 2004.
  36. ^ Cataldi, Mario; Ballatore, Andrea; Tiddi, Ilaria; Aufaure, Marie-Aude (June 22, 2013). "Good location, terrible food: detecting feature sentiment in user-generated reviews". Social Network Analysis and Mining. 3 (4): 1149–1163. CiteSeerX doi:10.1007/s13278-013-0119-7. ISSN 1869-5450. S2CID 5025282.
  37. ^ Liu, Bing; Hu, Minqing; Cheng, Junsheng (2005). "Opinion Observer: Analyzing and Comparing Opinions on the Web". Proceedings of WWW 2005.
  38. ^ Zhai, Zhongwu; Liu, Bing; Xu, Hua; Jia, Peifa (January 1, 2011). "Constrained LDA for Grouping Product Features in Opinion Mining". In Huang, Joshua Zhexue; Cao, Longbing; Srivastava, Jaideep (eds.). Advances in Knowledge Discovery and Data Mining. Lecture Notes in Computer Science. Vol. 6634. Springer Berlin Heidelberg. pp. 448–459. CiteSeerX doi:10.1007/978-3-642-20841-6_37. ISBN 978-3-642-20840-9.
  39. ^ Titov, Ivan; McDonald, Ryan (January 1, 2008). "Modeling online reviews with multi-grain topic models". Proceedings of the 17th international conference on World Wide Web. WWW '08. New York, NY, USA: ACM. pp. 111–120. arXiv:0801.1063. doi:10.1145/1367497.1367513. ISBN 978-1-60558-085-2. S2CID 13609860.
  40. ^ Liang, Bin; et al. (2022). "Aspect-based sentiment analysis via affective knowledge enhanced graph convolutional networks". Knowledge-Based Systems. 235: 107643. doi:10.1016/j.knosys.2021.107643. S2CID 237258427.
  41. ^ Ma, Yukun; et al. (2018). "Targeted aspect-based sentiment analysis via embedding commonsense knowledge into an attentive LSTM". Proceedings of AAAI. pp. 5876–5883.
  42. ^ Sharma, Raksha; Somani; Kumar; Bhattacharyya (2017). "Sentiment Intensity Ranking among Adjectives Using Sentiment Bearing Word Embeddings" (PDF). Association for Computational Linguistics: 547–552.
  43. ^ M. S. Akhtar, A. Ekbal and E. Cambria, "How Intense Are You? Predicting Intensities of Emotions and Sentiments using Stacked Ensemble [Application Notes]," in IEEE Computational Intelligence Magazine, vol. 15, no. 1, pp. 64-75, Feb. 2020, doi: 10.1109/MCI.2019.2954667.
  44. ^ X. Ouyang, P. Zhou, C. H. Li and L. Liu, "Sentiment Analysis Using Convolutional Neural Network," 2015 IEEE International Conference on Computer and Information Technology; Ubiquitous Computing and Communications; Dependable, Autonomic and Secure Computing; Pervasive Intelligence and Computing, 2015, pp. 2359-2364, doi: 10.1109/CIT/IUCC/DASC/PICOM.2015.349.
  45. ^ Y. Santur, "Sentiment Analysis Based on Gated Recurrent Unit," 2019 International Artificial Intelligence and Data Processing Symposium (IDAP), 2019, pp. 1-5, doi: 10.1109/IDAP.2019.8875985.
  46. ^ Cambria, E; Schuller, B; Xia, Y; Havasi, C (2013). "New avenues in opinion mining and sentiment analysis". IEEE Intelligent Systems. 28 (2): 15–21. CiteSeerX doi:10.1109/MIS.2013.30. S2CID 12104996.
  47. ^ Ortony, Andrew; Clore, G; Collins, A (1988). The Cognitive Structure of Emotions (PDF). Cambridge Univ. Press. Archived from the original (PDF) on November 23, 2015.
  48. ^ Stevenson, Ryan; Mikels, Joseph; James, Thomas (2007). "Characterization of the Affective Norms for English Words by Discrete Emotional Categories". Behavior Research Methods. 39 (4): 1020–1024. doi:10.3758/bf03192999. PMID 18183921. S2CID 6673690.
  49. ^ Sahlgren, Magnus; Karlgren, Jussi; Eriksson, Gunnar (2007). "Valence annotation based on seeds in word space". Proceedings of the Fourth International Workshop on Semantic Evaluations (SemEval-2007).
  50. ^ Kim, S. M.; Hovy, E. H. (2006). "Identifying and Analyzing Judgment Opinions." (PDF). Proceedings of the Human Language Technology / North American Association of Computational Linguistics conference (HLT-NAACL 2006). New York, NY. Archived from the original (PDF) on June 29, 2011.
  51. ^ Dey, Lipika; Haque, S. K. Mirajul (2008). "Opinion Mining from Noisy Text Data". Proceedings of the second workshop on Analytics for noisy unstructured text data, p.83-90.
  52. ^ Cambria, E; Hussain, A (2015). Sentic Computing: A Common-Sense-Based Framework for Concept-Level Sentiment Analysis. Springer. ISBN 9783319236544.
  53. ^ Akcora, Cuneyt Gurcan; Bayir, Murat Ali; Demirbas, Murat; Ferhatosmanoglu, Hakan (2010). "Identifying breakpoints in public opinion". SigKDD, Proceedings of the First Workshop on Social Media Analytics.
  54. ^ Cambria, Erik; Liu, Qian; Decherchi, Sergio; Xing, Frank; Kwok, Kenneth (2022). "SenticNet 7: A Commonsense-based Neurosymbolic AI Framework for Explainable Sentiment Analysis" (PDF). Proceedings of LREC. pp. 3829–3839.
  55. ^ Borth, Damian; Ji, Rongrong; Chen, Tao; Breuel, Thomas; Chang, Shih-Fu (2013). "Large-scale Visual Sentiment Ontology and Detectors Using Adjective Noun Pairs". Proceedings of ACM Int. Conference on Multimedia. pp. 223–232. Archived from the original on April 15, 2021. Retrieved November 2, 2017.
  56. ^ Socher, Richard; Perelygin, Alex; Wu, Jean Y.; Chuang, Jason; Manning, Christopher D.; Ng, Andrew Y.; Potts, Christopher (2013). "Recursive deep models for semantic compositionality over a sentiment treebank". In Proceedings of EMNLP: 1631–1642. CiteSeerX
  57. ^ "Case Study: Advanced Sentiment Analysis". Archived from the original on October 29, 2013. Retrieved October 18, 2013.
  58. ^ Mozetič, Igor; Grčar, Miha; Smailović, Jasmina (May 5, 2016). "Multilingual Twitter Sentiment Classification: The Role of Human Annotators". PLOS ONE. 11 (5): e0155036. arXiv:1602.07563. Bibcode:2016PLoSO..1155036M. doi:10.1371/journal.pone.0155036. ISSN 1932-6203. PMC 4858191. PMID 27149621.
  59. ^ Ogneva, M. "How Companies Can Use Sentiment Analysis to Improve Their Business". Mashable. Retrieved December 13, 2012.
  60. ^ Karlgren, Jussi, Magnus Sahlgren, Fredrik Olsson, Fredrik Espinoza, and Ola Hamfors. "Usefulness of sentiment analysis." In European Conference on Information Retrieval, pp. 426-435. Springer Berlin Heidelberg, 2012.
  61. ^ Karlgren, Jussi. "The relation between author mood and affect to sentiment in text and text genre." In Proceedings of the fourth workshop on Exploiting semantic annotations in information retrieval, pp. 9-10. ACM, 2011.
  62. ^ Karlgren, Jussi. "Affect, appeal, and sentiment as factors influencing interaction with multimedia information." In Proceedings of Theseus/ImageCLEF workshop on visual information retrieval evaluation, pp. 8-11. 2009.
  63. ^ Amigó, Enrique, Adolfo Corujo, Julio Gonzalo, Edgar Meij, and Maarten de Rijke. "Overview of RepLab 2012: Evaluating Online Reputation Management Systems." In CLEF (Online Working Notes/Labs/Workshop). 2012.
  64. ^ Amigó, Enrique, Jorge Carrillo De Albornoz, Irina Chugur, Adolfo Corujo, Julio Gonzalo, Tamara Martín, Edgar Meij, Maarten de Rijke, and Damiano Spina. "Overview of replab 2013: Evaluating online reputation monitoring systems." In International Conference of the Cross-Language Evaluation Forum for European Languages, pp. 333-352. Springer Berlin Heidelberg, 2013.
  65. ^ Amigó, Enrique, Jorge Carrillo-de-Albornoz, Irina Chugur, Adolfo Corujo, Julio Gonzalo, Edgar Meij, Maarten de Rijke, and Damiano Spina. "Overview of replab 2014: author profiling and reputation dimensions for online reputation management." In International Conference of the Cross-Language Evaluation Forum for European Languages, pp. 307-322. Springer International Publishing, 2014.
  66. ^ a b Wright, Alex. "Mining the Web for Feelings, Not Facts", New York Times, 2009-08-23. Retrieved on 2009-10-01.
  67. ^ "Sentiment Analysis on Reddit". September 30, 2014. Retrieved October 10, 2014.
  68. ^ Kirkpatrick, Marshall. ", ReadWriteWeb, 2009-04-15. Retrieved on 2009-10-01.
  69. ^ CORDIS. "Collective emotions in cyberspace (CYBEREMOTIONS)"[permanent dead link], European Commission, 2009-02-03. Retrieved on 2010-12-13.
  70. ^ Condliffe, Jamie. "Flaming drives online social networks ", New Scientist, 2010-12-07. Retrieved on 2010-12-13.
  71. ^ Tumasjan, Andranik; O.Sprenger, Timm; G.Sandner, Philipp; M.Welpe, Isabell (2010). "Predicting Elections with Twitter: What 140 Characters Reveal about Political Sentiment" Archived December 12, 2020, at the Wayback Machine. "Proceedings of the Fourth International AAAI Conference on Weblogs and Social Media"
  72. ^ Wood, Ian B.; Varela, Pedro L.; Bollen, Johan; Rocha, Luis M.; Gonçalves-Sá, Joana (2017). "Human Sexual Cycles are Driven by Culture and Match Collective Moods". Scientific Reports. 7 (1): 17973. arXiv:1707.03959. Bibcode:2017NatSR...717973W. doi:10.1038/s41598-017-18262-5. PMC 5740080. PMID 29269945.
  73. ^ Korkontzelos, Ioannis; Nikfarjam, Azadeh; Shardlow, Matthew; Sarker, Abeed; Ananiadou, Sophia; Gonzalez, Graciela H. (2016). "Analysis of the effect of sentiment analysis on extracting adverse drug reactions from tweets and forum posts". Journal of Biomedical Informatics. 62: 148–158. doi:10.1016/j.jbi.2016.06.007. PMC 4981644. PMID 27363901.
  74. ^ Tang, Huifeng; Tan, Songbo; Cheng, Xueqi (2009). "A survey on sentiment detection of reviews" (PDF). Expert Systems with Applications. 36 (7): 10760–10773. doi:10.1016/j.eswa.2009.02.063. S2CID 2178380. Archived from the original (PDF) on May 24, 2018.
  75. ^ a b Jakob, Niklas, et al. "Beyond the stars: exploiting free-text user reviews to improve the accuracy of movie recommendations." Proceedings of the 1st international CIKM workshop on Topic-sentiment analysis for mass opinion. ACM, 2009.
  76. ^ Minqing, Hu; Liu, Bing (2004). "Mining opinion features in customer reviews" (PDF). AAAI. 4 (4). S2CID 5724860. Archived from the original (PDF) on May 24, 2018.
  77. ^ Liu, Yang; Huang, Xiangji; An, Aijun; Yu, Xiaohui (2008). "Modeling and predicting the helpfulness of online reviews" (PDF). ICDM'08. Eighth IEEE international conference on Data mining. IEEE. pp. 443–452. doi:10.1109/ICDM.2008.94. ISBN 978-0-7695-3502-9. S2CID 18235238.
  78. ^ Bermingham, Adam; Smeaton, Alan F. (2010). "Classifying sentiment in microblogs". Proceedings of the 19th ACM international conference on Information and knowledge management (PDF). pp. 1833–1836. doi:10.1145/1871437.1871741. ISBN 9781450300995. S2CID 2084603.((cite book)): CS1 maint: date and year (link)
  79. ^ Lamba, Manika; Madhusudhan, Margam (2018). "Application of sentiment analysis in libraries to provide temporal information service: a case study on various facets of productivity". Social Network Analysis and Mining. 8 (1): 1–12. doi:10.1007/s13278-018-0541-y. S2CID 53047128.