It’s not just campaign season. It’s political polling season. We were hit with a handful last week and the results were quite different. Why? What gives? What do we need to consider when we hear about polls?

Polling is part science and part modeling guesswork.

Last week, Reboot Illinois commissioned an automated poll of the governor’s race that showed Rauner ahead by a significant margin. An interview poll commissioned by the Illinois Education Association showed a tighter race, as did a new kind of online poll taken by YouGov with The New York Times and CBS News that since has been criticized by the American Association for Public Opinion Research. The online poll included more than 100,000 respondents and covered contests nationwide. Obviously, it wouldn’t reach voters without Internet access.

Gregg Durham, chief operating officer for We Ask America, which has done polling for both Reboot Illinois and the Chicago Sun-Times, says what type of polling is being conducted is just one thing people should keep in mind when they read about polling. What are the others?

  • Who’s paying for it? Is it a poll paid for by a nonpartisan media firm or one pushing opposition research paid for by a candidate?

  • What’s tough to predict? This year, Illinois Democrats have loaded the ballot with questions to compel their supporters to vote. Will it work? How well? Will Rauner’s big, get-out-the-vote effort counteract this enough? Pollsters try to model their respondents to mirror Election Day turnout, but who votes this fall is an educated guess. Primary polling is always more challenging because turnout is tough to gauge and it keeps declining. It was especially so this year because pollsters weren’t sure how effective unions would be at getting Democrats to take Republican ballots. Turns out they were pretty effective.

  • Automated polls like those We Ask America does are good for simple questions like “For whom would you vote today?”

  • Live interview polls are good for more complex questions like “Why are you voting for Candidate X?” Those polls tend to take days to get a scientific sample and lots of news can break, changing some minds.

  • Online polling might be the future. It’s interesting, in part, because it allows pollsters to track the same people over time.

  • Still, how you contact someone is less important than whom you contact.

  • Pollsters call registered voters, often with a demonstrated record of recent voting. They typically start by asking people if they plan to vote. But, Durham noted, 95 percent of those called say they will vote. When is the last time you heard 95 percent of voters participated? Sadly, never.

  • Is a poll based on randomization or is a pollster prejudging whom they call? Read the explanation for how a poll was conducted.

  • Polls are a snapshot of one moment, so it’s best to follow them over time and study trends. Polls, especially this far from Election Day, are not predictions. Reading one poll is like reading “a single page in a novel and thinking you know what’s going on,” Durham said. “You need to read the whole thing and know who the author is.”

What about the Illinois governor’s race? It’s still early. “Anyone who thinks this isn’t going to tighten up,” Durham said, “hasn’t been paying attention.”

Pay attention to polling, but know it’s one tool. It shouldn’t determine whether or how you vote.

Madeleine Doubek is chief operating officer of Reboot Illinois.