How Are Political Polls Conducted?

ST. CLOUD -- As election day approaches, we're hearing a lot about polling, especially in the race for President. But how do these polls work, and are they accurate?

Jim Cottrill is the Co-Director of the St. Cloud State University Research Center. He says the polls are just estimates mostly using random digit dialing. He says they also weight the data to reflect the true population.

So we know if we get a 54 percent response rate from men, that's not the representation of the population, there are more women than men.  So what we have to do is give the women answers a little more weight to try to do a better job of representing the true population.

Cottrill says there are also statistical things they can do to make sure they get a sample from across the state.

He says some polling operators have moved online, but most are still done via the phone.

The great thing about phone numbers is because they are numbers, we can randomly generate them with a computer program, so there's no bias there, you're actually calling just whoever happens to pick up the phone.  Most polling operations are only about 10 to 15 percent landline now because if they are more than that they are not really going to be representative of the population.

Cottrill says one challenge with cellphones is women are less likely to answer a number they don't recognize than men are, so they need to weight the poll to reflect the true demographics of the region.

As for the 2016 polls which mostly had Hillary Clinton winning, he says they weren't wrong in that she actually did have more votes than Donald Trump, they were just interpreted incorrectly. While Trump lost the popular vote, he won the electoral vote.

Cottrill says he also believes this year's polls are probably more accurate too because Trump supporters were reluctant to show their support four years ago, but are now very vocal about their feelings toward him.