  We present a contribution to the debate on the predictability of social
events using big data analytics. We focus on the elimination of contestants in
the American Idol TV shows as an example of a well defined electoral phenomenon
that each week draws millions of votes in the USA. We provide evidence that
Twitter activity during the time span defined by the TV show airing and the
voting period following it, correlates with the contestants ranking and allows
the anticipation of the voting outcome. Furthermore, the fraction of Tweets
that contain geolocation information allows us to map the fanbase of each
contestant, both within the US and abroad, showing that strong regional
polarizations occur. Although American Idol voting is just a minimal and
simplified version of complex societal phenomena such as political elections,
this work shows that the volume of information available in online systems
permits the real time gathering of quantitative indicators anticipating the
future unfolding of opinion formation events.
