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About this Poll
The Iowa Poll, conducted Dec. 7-10 for The Des Moines Register and Bloomberg Politics by Selzer & Co. of Des Moines, is based on telephone interviews with 400 registered Iowa voters who say they definitely or probably will attend the 2016 Republican caucuses and 404 registered voters who say they definitely or probably will attend the 2016 Democratic caucuses.

Interviewers contacted 2,635 randomly selected active voters from the Iowa secretary of state’s voter registration list by telephone. Responses were adjusted by age, sex, and congressional district to reflect all active voters in the voter registration list.

Questions based on the subsamples of 404 likely Democratic caucus attendees or 400 likely Republican caucus attendees each have a maximum margin of error of plus or minus 4.9 percentage points. This means that if this survey were repeated using the same questions and the same methodology, 19 times out of 20, the findings would not vary from the percentages shown here by more than plus or minus 4.9 percentage points. Results based on smaller samples of respondents — such as by gender or age — have a larger margin of error.