Twitter and the health reforms in the English National Health Service.

Social media (for example Facebook and YouTube) uses online and mobile technologies to allow individuals to participate in, comment on and create user-generated content. Twitter is a widely used social media platform that lets users post short publicly available text-based messages called tweets that other users can respond to. Alongside traditional media outlets, Twitter has been a focus for discussions about the controversial and radical reforms to the National Health Service (NHS) in England that were recently passed into law by the current coalition Government. Looking at over 120,000 tweets made about the health reforms, we have investigated whether any insights can be obtained about the role of Twitter in informing, debating and influencing opinion in a specific area of health policy. In particular we have looked at how the sentiment of tweets changed with the passage of the Health and Social Care Bill through Parliament, and how this compared to conventional opinion polls taken over the same time period. We examine which users appeared to have the most influence in the 'Twittersphere' and suggest how a widely used metric of academic impact - the H-index - could be applied to measure context-dependent influence on Twitter.