Results of a new poll conducted by NBC-WSJ-Marist were spread. The poll asked participants from Ohio for whom they will vote: Republican nominee Donald Trump or Democrat nominee Hillary Clinton.
Historically, Ohio has been a battleground state, in which neither the Republican Party nor the Democratic Party has had overwhelming support to clinch that state's electoral college votes. This is why forecasts here are of particular interest.
NBC-WSJ-Marist poll results
According to the results, both candidates can draw on equal levels of support, each with 45.0% of the vote.
The poll was conducted from October 10 to October 12. A total of 724 likely voters responded. The sampling error is +/-3.6 points, which means that the levels of voter support for both candidates do not differ significantly.
Putting the results in context
As a general rule, however, one should not have too much faith in the results of single polls, as they sometimes incorporate large errors. Instead of trusting the results from single polls, the recommended strategy use combined polls or, even better, a combined forecast that incorporates different methods and data.
For the following analysis, we convert Trump's and Clinton's raw poll numbers into two-party vote shares. The results of the actual poll mean 50.0 % for Clinton and 50.0 % for Trump concerning the two-party vote share. On August 7 Clinton obtained only 46.9% in the NBC-WSJ-Marist poll and Trump obtained only 0.0%.
Comparison to the combined PollyVote
The most recent PollyVote predicts Clinton to gain 51.2% and Trump 48.8% of the two-party vote in Ohio. Clinton has 1.2 percentage points less when the results of the poll are compared to the combined PollyVote forecast for Ohio. The PollyVote forecast is therefore outside the poll's error margin.