How different turnout models change NBC News poll results

In close elections, voter turnout always matters. And while there are still many uncertainties ahead of November’s presidential election, one thing seems almost certain: It will be close, at least in many of the key states that will decide the election.

So the nonpartisan polling team behind the NBC News poll, Public Opinion Strategies and Hart Research Associates, devised an experiment.

What happens to the voting test in NBC News’ brand new national poll when assuming a turnout model that favors the Democratic Party versus one that favors the GOP?

The results won’t be a big surprise. But the exercise is insightful and shows how relatively small changes in the demographic makeup of the electorate could prove important in a close election.

Vice President Kamala Harris and former President Donald Trump are tied at 48% each in new October poll results from NBC News.

Assuming a turnout model that is more favorable to Republicans, Trump is ahead by 2 points, 49% to 47%. But a vote more favorable to Democrats puts Harris in the lead 49-46%. And neither scenario requires any outlandish assumptions.

What would this more favorable Democratic turnout look like? The number of female voters is increasing and the electorate is more racially diverse, with more college graduates and more from cities and suburbs.

The turnout model that looks better for Republicans is the opposite: a whiter electorate with more men and an increase in rural voters and those without college degrees.

But what’s really important is how little demographic movement is required to bring about these changes. It shows how important voter turnout can be in elections (not to mention the importance of the assumptions made in polls about who will vote).

In the pro-Democratic and pro-Republican turnout scenarios, the difference in the proportion of women in the electorate is only 1 point. In the pro-Democratic scenario, the white share of the electorate is lower than in the pro-Republican scenario, but only by 2 points.

A few percentage points difference in turnout based on age, race, education, urbanicity and a host of other factors can make a big difference, especially in a race that falls within the margin of error in all scenarios in this poll. This is why it’s so difficult to predict exactly what will happen in a close election – and it’s one of the main reasons why there are differences in polls before elections.

The NBC News poll of 1,000 registered voters, 898 of whom were reached by cell phone, was conducted Oct. 4-8. The overall margin of error is plus/minus 3.1 percentage points.