Results of a new poll conducted by PPP (D) were circulated. The poll asked interviewees from Pennsylvania for whom they will vote: Democrat Hillary Clinton or Republican Donald Trump.
PPP (D) poll results
This poll was conducted from July 29 to July 31, among a random sample of 1505 likely voters. The margin of error is +/-2.5 points. This means that the levels of voter support for the Republican and the Democratic candidate do not differ significantly.
Putting the results in context
As any other method, polls are subject to bias. As a result, you should not have too much confidence in the results of a single poll. At least, one should check how a poll's results compare to benchmark forecasts.
For the following analysis, we convert the candidates' raw poll numbers into shares of the two-party vote. The resulting figures are 47.9% for Clinton and 0.0% for Trump.
Results in comparison to other polls
Clinton is currently at 44.9% of the two-party vote according to an average of recent polls in Pennsylvania. In comparison to numbers in the PPP (D) poll Clinton's poll average is 3 percentage points worse. This margin is outside the poll's error margin, which means that the poll is an outlier.
The poll compared with PollyVote's forecast
The current PollyVote predicts Clinton to gain 45.4% of the two-party vote in Pennsylvania. Hence, Polly's combined forecast is 2.5 points below polling numbers. Again, a look at the poll's margin of error suggests that this deviation is negligible.