Results of a new poll carried out by The Simon Poll/SIUThe Simon Poll/SIU were announced. The poll asked participants from Illinois for whom they will vote: Democrat Hillary Clinton or Republican Donald Trump.
The Simon Poll/SIUThe Simon Poll/SIU poll results
The results show that 53.0% of interviewees are going to vote for former First Lady Hillary Clinton, whereas 28.0% are going to vote for businessman Donald Trump.
The poll was carried out from September 27 to October 2 among 865 likely voters. There is a sampling error of +/-3.3 percentage points. Considering this error margin, the gap between both candidates is statistically significant.
Putting the results in context
In general, however, a good strategy is to not have too much faith in the results of single polls, because they often incorporate large errors. Rather than relying on results from single polls, the best practice scientific advice is to use combined polls or, even better, the combined PollyVote forecast that uses forecasts from different methods, each of which uses different data.
To make the results comparable to forecasts from other methods, one can translate them into shares of the two-party vote. This yields figures of 65.4% for Clinton and 34.6% for Trump.
Comparison to other polls
An average of recent polls in Illinois sees Clinton at 59.2% of the two-party vote. Compared to her numbers in the The Simon Poll/SIUThe Simon Poll/SIU poll Clinton's poll average is 6.2 percentage points lower. This deviation is outside the poll's sampling error, which suggests that the poll is an outlier.
The poll compared with PollyVote's prediction
The most recent PollyVote predicts Clinton to gain 60.2% of the two-party vote in Illinois. Hence, Polly's prediction is 5.2 points below her polling numbers. The PollyVote forecast is therefore outside the poll's error margin.