Twitter and the traditional media: Who is the real agenda setter?

The rise of social media and social network sites has re-opened the debate on the role of Internet as an 'uncoerced' public sphere that provides room for (direct) e-democracy and deliberation through the unmediated diffusion of news. The reduced costs required to diffuse information and the bottom-up networked structure of social media can potentially undermine the dominance of traditional media outlets and preventing any attempt to hide inconvenient political news. In light of this, the present paper investigates whether the general public, through social media, can act as agenda-setter or, conversely, the agenda-setting power of traditional media outlets is unchanged. For this purpose, we focus on the heated debate on corruption political scandals and reform of public funding of parties that took place in Italy between April and July 2012, and we improve on existing literature by adopting innovative and efficient statistical methods, like the lead-lag analysis and a supervised technique of sentiment analysis, to evaluate first-level and second-level agenda setting effects. Our results show that traditional mass media keep their first-level agenda setting power. However, first-level agenda setting power does not imply that traditional media influence the online debate, as long as we find a marked difference in the degree of antipolitics sentiment expressed on social media compared to the level of negativity observed in the frame of stories issued by traditional media outlets. [ABSTRACT FROM AUTHOR]