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About this Poll
The Iowa Poll, conducted Sept. 21-24 for The Des Moines Register by Selzer & Co. of Des Moines, is based on interviews with 800 Iowans ages 18 or older. Interviewers contacted households with randomly selected landline and cellphone numbers. Responses were adjusted by age, sex and congressional district to reflect the general population based on recent Census data.

Questions based on the sample of 800 Iowa adults have a maximum margin of error of plus or minus 3.5 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 3.5 percentage points. Questions based on a subsample of 546 likely voters have a margin of error of plus or minus 4.2 percentage points. Results based on smaller samples of respondents — such as by gender or age — have a larger margin of error.