Silent Voices: Public Opinion and Political Participation in America. By Adam J. Berinsky. Princeton: Princeton University Press, 2004. 224p. $35.00.

Polls, Adam Berinsky warns, are flawed. The source of this flaw is what he labels “exclusion bias,” defined as “the exclusion of the preferences of the sometimes sizable portion of the public who say they ‘don't know’ where they stand on the issues of the day” (p. 2).