Politicians and corporations cannot only measure public opinion but also manipulate and create it. And they have been doing so since the 1930s when serious polling began. And as Professor Susan Herbst, author of Numbered Voices: How Opinion Polling Has Shaped American Politics, explains early public opinion research raised hopes for better democratic practice but also led to fears for the future. 
Owen Bennett-Jones is a freelance journalist and writer. A former BBC correspondent and presenter he has been a resident foreign correspondent in Bucharest, Geneva, Islamabad, Hanoi and Beirut. He is recently wrote a history of the Bhutto dynasty which was published by Yale University Press.
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