A randomised trial shows that the power of the press is real

MALCOLM X, an American political activist, described the media as the most powerful entity on Earth, "because they control the minds of the masses". Some journalists may find this proposition flattering, but though those who study such things agree newspapers exert some influence over their readers, the effect has proved devilishly difficult to quantify. Now, Gary King of Harvard University and his colleagues have measured the impact of stories from almost three dozen different news sources on t...