On August 1, NBC-WSJ-Marist released the results of a new poll, in which respondents from Pennsylvania were asked for whom they will vote: Hillary Clinton or Donald Trump.
NBC-WSJ-Marist poll results
According to the results, 45.0% of interviewees said that they would vote for former First Lady Hillary Clinton, while 36.0% are going to vote for billionaire Donald Trump.
The poll was conducted from July 5 to July 10. A total of 829 registered voters responded. There is a sampling error of +/-3.4 percentage points. Considering this error margin, the gap between both candidates is statistically significant.
Putting the results in context
Single polls can incorporate large errors, which is why they should be treated with caution. At least, one should examine how a poll's results compare to benchmark forecasts.
To make the results comparable to forecasts from benchmark methods, one can translate them into shares of the two-party vote. This yields figures of 55.6% for Clinton and 44.4% for Trump.
Comparison to other polls
If we look at an average of Pennsylvania polls, Clinton's current two-party vote share is at 52.5%. In comparison to her numbers in the NBC-WSJ-Marist poll Clinton's poll average is 3.1 percentage points lower. This deviation is within the poll's sampling error, which means that the poll is not an outlier.
Results compared to the combined PollyVote forecast
The most recent PollyVote expects Clinton to gain 52.6% of the two-party vote in Pennsylvania. Hence, the PollyVote is 3.0 points below her polling numbers. Again, a look at the poll's sampling error indicates that this difference is insignificant.