On November 2, Des Moines Register released the results of a new poll, in which respondents from Iowa were asked for whom they will vote: Republican nominee Donald Trump or Democrat nominee Hillary Clinton.
Iowa is traditionally a battleground state, where Republicans and Democrats have historically gained similar levels of support among voters. Therefore, the election outcome here is regarded critical in determining the overall result of the presidential election.
Des Moines Register poll results
The results show that 39.0% of interviewees would cast a ballot for former Secretary of State Hillary Clinton, while 43.0% intend to vote for businessman Donald Trump.
The poll was conducted from October 3 to October 6 with 642 likely voters. The sampling error is +/-3.9 points, which means that the poll results for the candidates of both parties do not differ significantly.
Putting the results in context
Single polls may incorporate large errors, and should be treated with caution. Instead of relying on results from single polls, the evidence-based approach is to rely on combined polls or, even better, the combined PollyVote forecast that draws upon different methods and data.
To make the results comparable to forecasts from other methods, you can convert them into two-party vote shares. The respective figures are 47.6% for Clinton and 52.4% for Trump.
Comparison to other polls
An average of recent polls in Iowa has Trump at 51.5% of the two-party vote. Compared to his numbers in the Des Moines Register poll Trump's poll average is 0.9 percentage points worse. This margin is within the poll's margin of error, which means that the poll is not an outlier.
Results compared to the combined PollyVote forecast
The most recent PollyVote foresees Trump to gain 49.7% of the two-party vote in Iowa. This means that the combined PollyVote is 2.7 points below his polling numbers. The PollyVote forecast is thus in line with the poll's margin of error.