Wash. Post: Several Variables Could Affect Caucus Outcome

By the numbers, Donald Trump and Hillary Clinton are front-runners to win Monday night's Iowa caucuses, but there are still several variables that could give the nods to their nearest rivals, Ted Cruz and Bernie Sanders.

Trump has a seven-point lead for the GOP win according to The Washington Post, quoting Pollster, while Clinton has a narrow, three-point lead over Sanders.
 
But there are still questions remaining over whether the polls predict who will come out to participate in the caucuses, John Sides, an associate professor of political science at George Washington University, wrote in The Post's analysis.

Polls that call confirmed registered voters show a larger Clinton lead, while Trump's support is polled from people who say they'll vote this time, even though they do not have a record of voting in primary elections before, Sides notes.

Nate Silver's FiveThirtyEight website is scoring the race differently, with
a poll-based forecast based only on state polls gives Clinton a 67 percent chance of winning, Sanders, 33 percent, Trump 46 percent, and Cruz, 39 percent.

Further, 538 forecasts argue, state polls alone have not predicted previous caucus winners, but endorsements and national polls also count.

And there are prediction markets, reports The Post, which give an incentive to make accurate predictions based on aggregated information.

Using this method, the markets lean more toward Trump than forecasts based on state polls, giving Trump as of Monday morning a 66 percent chance of pulling out a win, with Cruz drawing a 29 percent chance. The markets are about the same as the 538 forecasts for the Democratic side, giving Clinton a 76 percent chance compared to 24 percent for Sanders.

By averaging the forecasts, Sides argues, the numbers point to victories for Clinton with 68 percent of wining and Trump with 57 percent.

"However, 68 percent and 57 percent are far from 100 percent," he writes. "I said there was a 32 percent chance or a 43 percent chance you'd be hit by a car the next time you crossed the street, you'd definitely think twice. A lot of uncertainty remains."

Further, he said winning in Iowa is not necessary for winning the nomination race, even though it does boost news coverage and poll numbers in other states.

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