On October 10, Quinnipiac released the results of a new poll, in which respondents from Pennsylvania were asked for whom they will vote: Democrat Hillary Clinton or Republican Donald Trump.
Quinnipiac poll results
The results show that 51.0% of respondents will cast a ballot for former First Lady Hillary Clinton, while 45.0% plan to vote for businessman Donald Trump.
This poll was conducted from October 10 to October 16, among a random sample of 660 likely voters. Given the poll's margin of error of +/-3.8 percentage points, the results reflect a statistical tie.
Putting the results in context
In general, however, one should not have too much faith in the results of single polls, because they can incorporate large errors. At the very least, one should check how a poll's results compare to benchmark forecasts.
In order to make the results comparable to benchmark forecasts, one can convert them into two-party vote shares. The resulting figures are 53.1% for Clinton and 46.9% for Trump. To compare: Only 44.7% was gained by Clinton in the Quinnipiac poll on August 7, for Trump this result was only 0.0%.
Comparison to other polls
An average of recent polls in Pennsylvania sees Clinton at 53.7% of the two-party vote. Relative to her numbers in the Quinnipiac poll Clinton's poll average is 0.6 percentage points better. This margin is within the poll's sampling error, which means that the poll is not an outlier.
The poll compared with PollyVote's prediction
The current PollyVote forecasts Clinton to gain 53.8% of the two-party vote in Pennsylvania. This means that the combined PollyVote is 0.7 points above her polling numbers. Again, a look at the poll's error margin reveals that this deviation is negligible.