Sentiment analysis - Our approach and use cases
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I. Introduction to Sentiment Analysis and its applications. II. How to approach Sentiment Analysis? III. 2015 Elections in Poland on Twitter.com & Onet.pl.
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Sentiment analysis - Our approach and use cases
- 1. Sentiment Analysis our approach and use cases Karol Chlasta Antoni Sobkowicz ś dBConf 2015
- 2. Agenda 2015 Elections in Poland on Twitter.com & Onet.pl Introduction to Sentiment Analysis and its applications Questions & Answers How to approach Sentiment Analysis?
- 3. Introduction to Sentiment Analysis and its applications
- 4. ➔ Author’s sentiment ◆ in all text ◆ in particular sentences ◆ towards an entity(s) ◆ towards specific aspects(s) ➔ Author’s emotions ◆ basic vs other emotions ➔ When to automate? ◆ many texts ◆ texts are untagged ◆ gaps in annotation Sentiment vs Emotion Analysis
- 5. Sentiment Analysis or Opinion Mining ➔ Owner of the opinion ➔ Entity vs aspect ➔ Type of opinion(s) expressed ◆ like / dislike ◆ optimism / pessimism ◆ evaluation, confidence, familiarity ◆ polarization ➔ Value of opinion ➔ Event of sentiment expression He recorded white Russian trucks crossing the border and progressing fast towards Białystok. The candidate looked confident, well prepared and was even very well received by the audience, but lost the debate after answering that question.
- 6. Sample Applications Politics - forecasting sentiment towards a candidate, political party or reform, social issue. Review - to draw a conclusion if this review is positive or negative Market monitoring - Clients’ comments about our company or the competition. Product - what people think about the new...
- 9. Approaches ➔ Dictionary methods ◆ Manual or (self)automatic ➔ Statistical methods ◆ Training sets ◆ Various descriptive features ● Words ● Detection of coexistence of words ● Punctuation ● Syntax ● Emoticons ● Language specific analysis ○ http://nlp.stanford.edu/sentiment/
- 10. Data Gathering ➔ Social Networks ◆ Many social networks provide APIs ➔ Thematic websites ◆ Need to create customized scrappers Important thing - before data gathering we need to correctly select media we are covering!
- 11. Manually Tagging Sentiment ➔ Manually tagged sentiment data can be used to create sentiment dictionaries and reference (training) sentiment data for experiments ➔ Data should be tagged by several taggers, because, especially in politics, Positive and Negative are very subjective ➔ Data should also be tagged in a way that combats effects associated with Negative Bias ➔ Negative Bias is an effect which results in negative feelings and events are treated as more important by human brain. “ta d... wykrzykiwała codzień pod krzyżem” tagged as neutral “nie dostal sie, na szczescie, do tego palacu, wiec wystaje poden co chwila :)) niedoczekanie twoje, kaczynski!” tagged as negative
- 12. 2015 Elections in Poland on Twitter.com & Onet.pl
- 13. Twitter.com and Onet.pl (+ Wp.pl) Twitter.com Over 11,000 tweets related to 10 profiles of candidates on May 10th Onet.pl and Wp.pl Over 2000 articles with one of the tags related to election (Andrzej Duda, Bronisław Komorowski, Paweł Kukiz, Ewa Kopacz, Beata Szydło) between 20.05 and 20.08 (second round of election to presidential swearing-in). Over 1.5m comments written by the users. Additional 12,000+ comments from years 2009-2011 for evaluation purposes
- 14. Twitter.com
- 15. Implementation Technology ➔ R 3.2.0 running on i686-pc-linux-gnu, RStudio 0.98.1103 ➔ twitteR, dplyr, stringi, ggplot2, tm, e1071, RTextTools Data ➔ 11,744 tweets related to 10 profiles of candidates from May 10th, simple sentiment scoring algorithm ➔ Lexicon of 2000 positive & 3693 negative Polish words. 18 positive and 22 negative emoticons ➔ 6040 tweets, excluding all neutral used to evaluate Naive Bayes, Maximum Entropy, Support Vector Machines, and Tree sentiment classifiers using 70/30 principle Results ➔ Two approaches: Naive Bayes and Maximum Entropy achieved the best accuracy (71.76% and 77.32% respectively)
- 16. Onet.pl & Wp.pl
- 17. Step I Technology ➔ .NET ➔ Python 2.7 + Scrapy ➔ Java 8 Data ➔ 1,533,035 comments in 2057 articles total ◆ 923 manually sentiment annotated comments ➔ 5850 comments from 2011, site Gazeta.pl used for lexicon generation (TRAIN-POL) ➔ 31095 tweets used for lexicon generation (TRAIN- TWIT ➔ Evaluated methods: Naive Bayes (NB) and three dictionary based methods Results ➔ Two approaches: Naive Bayes and Simple Dictionary Addition achieved the best accuracy (76% and 78% respectively)
- 19. Step II Technology ➔ .NET ➔ Python 2.7 + Scrapy ➔ Java 8 Data ➔ 1,533,035 comments in 2057 articles total ◆ 923 manually sentiment annotated comments ➔ 6448 comments from 2011, site Gazeta.pl ➔ 4592 comments from 2011, site Wyborcza.pl ➔ 7177 comments from 2010, site Gazeta.pl ➔ Lexicons generated from comments ➔ Datasets cross-tested using dictionaries created with different datasets Results ➔ Old datasets can be used to annotate new texts despite 4 year difference
- 20. Step III Technology ➔ Java 8 Data ➔ 1,533,035 comments in 2057 articles total ➔ Lexicon generated using manually sentiment tagged data (from Gazeta.pl 2010, 2011 and Wyborcza.pl 2011) ➔ Algorithm threshold tweaked to have both good binary and 3-category classification Results ➔ Most comments are negative!
- 21. Summary
- 22. Questions? Karol Chlasta (@KarolChlasta) Antoni Sobkowicz http://opi-lil.github.io/