NBC-WSJ-Marist published the results of a new poll. In this poll, interviewees from Pennsylvania were asked for whom they will vote: Republican Donald Trump or Democrat Hillary Clinton.
NBC-WSJ-Marist poll results
The results show that 48.0% of interviewees are going to cast a ballot for former New York Senator Hillary Clinton, whereas 37.0% are going to vote for real estate developer Donald Trump.
The poll was conducted from August 3 to August 7 among 834 registered voters. The margin of error is +/-3.4 percentage points. This means that the levels of voter support for both parties' candidates differ significantly.
Putting the results in context
Single polls often include large errors, and should be interpreted with caution. Rather than trusting the results from single polls, research in forecasting recommends to use combined polls or, even better, a combined forecast that incorporates forecasts from different methods, each of which draws upon different data.
To make the results comparable to benchmark forecasts, you can translate them into two-party vote shares. The resulting figures are 56.5% for Clinton and 43.5% for Trump.
Comparison to other polls
Clinton currently achieves 54.7% of the major two-party vote according to an average of recent polls in Pennsylvania. Compared to her numbers in the NBC-WSJ-Marist poll Clinton's poll average is 1.9 percentage points lower. This difference is within the poll's margin of error, which means that the poll is not an outlier.
Results compared to the combined PollyVote prediction
The current PollyVote predicts Clinton to gain 54.5% of the two-party vote in Pennsylvania. Hence, Polly's combined forecast is 2.0 points below her polling numbers. The PollyVote forecast is thus within the poll's error margin.