Latest Suffolk University poll in Iowa: Clinton and Trump in a tossup
Suffolk University published the results of a new poll. In this poll, participants from Iowa were asked for whom they will vote: Hillary Clinton or Donald Trump.
In Iowa, the popular vote is usually close. Therefore, the state is commonly viewed as a battleground state, which makes it particularly interesting from a forecasting perspective.
Suffolk University poll results
According to the results, 40.0% of respondents indicated that they would cast a ballot for former Secretary of State Hillary Clinton, whereas 41.0% would vote for businessman Donald Trump.
The poll was in the field between August 8 and August 10. The sample size was 500 likely voters. The sampling error is +/-4.4 percentage points, which means that the levels of voter support for Trump and Clinton do not differ significantly.
Putting the results in context
Individual polls may include large errors, which is why they should be interpreted with caution. Instead of trusting the results from single polls, the evidence-based approach is to use combined polls or, even better, the combined PollyVote forecast that includes forecasts from different methods, each of which includes different data.
To make the results comparable to benchmark forecasts, one can convert them into shares of the two-party vote. This yields figures of 49.4% for Clinton and 50.6% for Trump.
Comparison to other polls
An average of recent polls in Iowa has Trump at 50.5% of the two-party vote. This value is 0.1 percentage points lower than her respective numbers in the Suffolk University poll. This difference is within the poll's sampling error, which means that the poll is not an outlier.
Comparison to the combined PollyVote
The most recent PollyVote forecasts Trump to gain 48.4% of the two-party vote in Iowa. That is, the PollyVote forecast is 2.2 points below her polling numbers. The PollyVote forecast is thus in line with the poll's error margin.