Results of a new poll conducted by PPP (D) were released. The poll asked respondents from Pennsylvania for whom they will vote: Hillary Clinton or Donald Trump.
PPP (D) poll results
Of those who responded, 49.0% said that they would vote for former First Lady Hillary Clinton, whereas 45.0% declared that they would give their vote to businessman Donald Trump.
The poll was conducted from July 29 to July 31 among 1505 likely voters. There is a sampling error of +/-2.5 percentage points. Considering this error margin, the race is currently a statistical tie.
Putting the results in context
As a general rule, however, you should not have too much faith in the results of single polls, since they sometimes incorporate large errors. Instead of trusting the results from single polls, research in forecasting recommends to rely on combined polls or, even better, a combined forecast that draws upon forecasts from different methods, each of which draws upon different data.
For the following analysis, we translate the candidates' raw poll numbers into shares of the two-party vote. This yields figures of 52.1% for Clinton and 47.9% for Trump.
Comparison to other polls
If we look at an average of Pennsylvania polls, Clinton's two-party vote share is currently at 54.6%. This value is 2.5 percentage points higher than her respective numbers in the PPP (D) poll. This margin is within the poll's sampling error, which means that the poll is not an outlier.
Comparison to the combined PollyVote
The current PollyVote foresees Clinton to gain 54.5% of the two-party vote in Pennsylvania. That is, the PollyVote forecast is 2.4 points above her polling numbers. The PollyVote forecast is thus within the poll's margin of error.