The Simon Poll/SIU published the results of a new poll. In this poll, interviewees from Illinois were asked for whom they will vote: Democrat Hillary Clinton or Republican Donald Trump.
The Simon Poll/SIU poll results
Of those who replied, 53.0% said that they intend to vote for former Secretary of State Hillary Clinton, whereas 28.0% revealed that they would give their vote to real estate developer Donald Trump.
This poll was conducted from September 27 to October 2, among a random sample of 865 likely voters. The error margin is +/-3.3 points. This means that the poll results for the candidates of both parties differ significantly.
Putting the results in context
Single polls can incorporate large errors, which is why they should be treated with caution. Instead of relying on results from single polls, the best practice is to consult combined polls or, even better, a combined forecast that uses forecasts from different methods, each of which draws upon different data.
To make the results comparable to benchmark forecasts, we convert them into two-party vote shares. This procedure results in figures of 65.4% for Clinton and 34.6% for Trump.
Results compared to other polls
If we look at an average of Illinois polls, Clinton's current two-party vote share is at 59.2%. In comparison to her numbers in the The Simon Poll/SIU poll Clinton's poll average is 6.2 percentage points worse. This deviation is outside the poll's sampling error, which suggests that the poll is an outlier.
Comparison to the combined PollyVote
The current PollyVote anticipates Clinton to gain 59.5% of the two-party vote in Illinois. Hence, Polly's combined forecast is 5.9 points below her polling numbers. Again, a look at the poll's error margin shows that this difference is significant.