NBC-WSJ-Marist released the results of a new poll, in which respondents from Ohio were asked for whom they will vote: Republican Donald Trump or Democrat Hillary Clinton.
In Ohio, the election outcome is usually close. This is why the state is commonly viewed as a battleground state, which makes it particularly interesting from a forecasting perspective.
NBC-WSJ-Marist poll results
Of those who responded, 43.0% said that they will vote for former New York Senator Hillary Clinton, while 38.0% said that they would give their vote to businessman Donald Trump.
The poll was conducted between August 3 and August 7. The sample size was 889 registered voters. There is a sampling error of +/-3.3 percentage points. Considering this error margin, the race is currently a statistical tie.
Putting the results in context
In general, however, you should not have too much faith in the results of single polls, because they often contain large errors. Rather than relying on results from single polls, one should use combined polls or, even better, the combined PollyVote forecast that relies on forecasts from different methods, each of which relies on different data.
In order to make the results comparable to forecasts from other methods, you can convert them into two-party vote shares. This yields figures of 53.1% for Clinton and 46.9% for Trump.
Results vs. other polls
Looking at an average of Ohio polls, Clinton's current two-party vote share is at 51.5%. Compared to her numbers in the NBC-WSJ-Marist poll Clinton's poll average is 1.6 percentage points worse. This difference is within the poll's margin of error, which means that the poll is not an outlier.
Comparison to the combined PollyVote
The most recent PollyVote foresees Clinton to gain 51.0% of the two-party vote in Ohio. This means that Polly's forecast is 2.1 points below her polling numbers. Again, a look at the poll's sampling error suggests that this difference is negligible.