Results of a new poll conducted by Gravis were released. The poll asked interviewees from Colorado for whom they will vote: Republican nominee Donald Trump or Democrat nominee Hillary Clinton.
In Colorado, the popular vote is usually close. This is why the state is commonly viewed as a battleground state, which makes it particularly interesting from a forecasting perspective.
Gravis poll results
Of those who answered the question, 43.0% said that they will vote for former First Lady Hillary Clinton, whereas 41.0% said that they would give their vote to real estate developer Donald Trump.
The poll was carried out from July 7 to July 8 with 1313 adults. The sampling error is +/-2.7 percentage points. This means that the levels of voter support for the Democratic and the Republican candidate do not differ significantly.
Putting the results in context
In general, however, one should not have too much faith in the results of single polls, since they can incorporate large errors. Rather than trusting the results from single polls, the best practice scientific advice is to use combined polls or, even better, a combined forecast that includes different methods and data.
To make the results comparable to forecasts from other methods, we convert them into two-party vote shares. This yields figures of 51.2% for Clinton and 48.8% for Trump.
Comparison to other polls
If we look at an average of Colorado polls, Clinton's current two-party vote share is at 54.9%. Compared to her numbers in the Gravis poll Clinton's poll average is 3.7 percentage points higher. This deviation is outside the poll's margin of error, which suggests that the poll is an outlier.
Comparison to the combined PollyVote
The most recent PollyVote foresees Clinton to gain 53.1% of the two-party vote in Colorado. That is, Polly's combined forecast is 1.9 points above her polling numbers. The PollyVote forecast is therefore within the poll's error margin.