This document discusses sentiment analysis and different approaches for measuring sentiment at scale. It explains that while crowdsourcing is slow and expensive, machines can be taught to analyze sentiment through machine learning by training them on large amounts of human-tagged text. However, accuracy depends on the type of language and domain. The best approach is typically a combination of machine analysis for large volumes supplemented by manual review of important texts.

1. Sentiment analysis

2. Who am I? personal tags: giles palmer founder and ceo of brandwatch.net – buzz monitoring to the stars taller than your average joe please sponsor my tash at: www.movember.com

3. www.brandwatch.net | 3 Sentiment – so why’s that important then?

4. Politicians are obsessed with it

5. www.brandwatch.net | 5 Companies like it because it can help predict….

6. www.brandwatch.net | 6 Sales

7. Some sentiment stats www.brandwatch.net | 7

8. www.brandwatch.net | 8 The sentiment of the web Sample size 400,000 web pages about 1,000 different things

9. People don’t agree with each other all the time www.brandwatch.net | 9 (Arsenal 2 : 1 Man Utd) In our tests, people agree on sentiment 85% of the time

10. www.brandwatch.net | 10 Top ‘Brands’ in October – English speaking web Volume ‘000s Sentiment * Volume Sentiment

11. www.brandwatch.net | 11

12. www.brandwatch.net | 12

13. How do you measure the sentiment of millions of webpages? www.brandwatch.net | 13

14. Crowdsource ? www.brandwatch.net | 14

15. Downsides to crowdsourcing www.brandwatch.net | 15 Slow (compared to machines) Inconsistent Expensive e.g. Article takes 2 minutes so 30 articles per hour You need native speakers, so £6/hr => Article costs £0.2 to read 10,000 articles * £0.2 = £2,000 (Twitter is cheaper)

16. Machines ? www.brandwatch.net | 16 Q: Can we RELIABLY get a machine to do sentiment analysis ? A: Kind of Q: How ? A: You teach it to mimic your own behaviour using a branch of Artificial Intelligence called Machine Learning

17. Teaching machines www.brandwatch.net | 17 Decide what text to feed in Train them (lots) Audit and improve (lots) It’s not quick

18. www.brandwatch.net | 18 BSkyB has struck a deal with Apple to launch its mobile TV service providing live access to sport including Premier League football matches on the iPhone. From today the service, Sky Mobile TV, will be made available to iPhone and iPod Touch owners via a new application at the Apple App Store. The application allows iPhone owners to stream live TV – via a Wi-Fi connection – from a selection of channels including the Sky Sports portfolio, Sky Sports News, ESPN, At The Races and Sky News. The sports and news package will cost phone owners £6 a month. Sky's mobile TV service allows iPhone owners to access live televised matches from the Barclays Premier League, Scottish Premier League and Football League, as well as sport such as European Tour golf, Premiership rugby and international and domestic cricket. The application is free to download and is being made available to all iPhone owners regardless of which mobile network they are signed to. Sky Mobile TV is already available, for £5 a month, on the 3G networks of Vodafone, Orange and T-Mobile. In the past year BSkyB has launched a number of applications in the Apple App Store, for football, cricket and news updates, and claims more than 2m downloads so far. "In less than a year we've already seen millions of downloads of Sky's various iPhone apps," said David Gibbs, the general manager for mobile at Sky. "Now, by launching our new Sky Mobile TV app, we are able to combine the demand for great live TV on the move with the quality of experience offered through the iPhone and iTouch." As part of the launch of the service mobile network operator O2 is giving its iPhone customer base three months' free subscription to Sky Mobile TV.

19. www.brandwatch.net | 19

20. How to train machines www.brandwatch.net | 20 A trained native speaker reads something and tags it Feed that data into the program Repeat many times The program use this information to build up statistical maps Then you feed an untagged snippet in and the machine gives it the tag that’s statistically closest to its training

22. Type of language used has big effect eg Insurance news vs online gaming forums

24. Accuracy ranges from 94% for Swedish videogames to 50% for Portuguese telecomGood target is 75% which is achievable

25. The best approach www.brandwatch.net | 22 For small volumes – crowdsource For large volumes – use machines, but also look at the most important mentions manually

27. It’s not as good as people (who are native speakers)

28. The text you feed into the program is critical

29. Machines need a lot of training