CBS News/YouGov published the results of a new poll. In this poll, respondents from Iowa were asked for whom they will vote: Democrat Hillary Clinton or Republican Donald Trump.
Iowa is traditionally a battleground state, where the Republican and Democratic candidates have often achieved similar voter support. This is the reason why the election outcome in that state is considered critical in determining which party will win the majority of electoral votes.
CBS News/YouGov poll results
According to the results, billionaire Donald Trump and former Secretary of State Hillary Clinton can draw on identical levels of support, each with 40.0% of the vote.
This poll was conducted from August 17 to August 19, among a random sample of 987 likely voters. Taking into account the poll's sampling error of +/-4.0 percentage points, the results reflect a statistical tie.
Putting the results in context
As any other method, polls are subject to bias. In general, you should not be too confident the results of an individual poll. Rather, one should examine how a poll's results compare to benchmark forecasts.
In order to make the results comparable to forecasts from benchmark methods, you can convert them into shares of the two-party vote. The results of the actual poll mean 50.0 % for Clinton and 50.0 % for Trump for the two-party vote share.
Comparison to other polls
An average of recent polls in Iowa has Clinton at 49.5% of the two-party vote. In comparison to the average forecast of other polls Clinton performed 0.5 percentage points better in the poll. This deviation is outside the poll's margin of error, which suggests that the poll is an outlier.
Comparison to the combined PollyVote
The most recent PollyVote predicts Clinton to gain 51.6% and Trump 48.4% of the two-party vote in Iowa. Clinton has 1.6 percentage points less when the results of the poll are compared to the combined PollyVote forecast for Iowa. Again, a look at the poll's sampling error indicates that this difference is significant.