MICHIGAN — Hillary Clinton led Bernie Sanders by 21 points heading into Michigan's March primary election, according to the Real Clear Politics polling average.
But Sanders won Michigan 50 to 48 percent, even after nearly every public poll taken within the month leading to the election had Clinton leading by double digits.
Fast forward to August and Clinton, now the Democratic nominee, is leading her Republican rival by several percentage points, with one statewide poll showing her with as much as a 10 point lead over Donald Trump.
Some experts called Michigan's primary poll outcome a "train wreck." Will Michigan face a similar situation in the general election?
Grand Valley State University political science professor Don Zinman says it's not likely.
“Primaries are just harder to poll because there’s a greater chance of divergent results," Zinman said, noting Michigan's open primary set-up which doesn't require voters to register a party affiliation before casting a ballot.
"There’s a smaller pool of voters so there’s just a greater likelihood that the results are going to misfire."
Overall, pollsters face an increasing number of methodological problems as the traditional means of surveying voters has become outdated or outright obsolete in recent decades, a reality Zinman acknowledges.
"The response rates over the years have gone down, people just don’t want to answer a poll and people are able to screen calls out too," he said. "You’re also dealing with a growing number of people who don’t even have a landline and are only reachable by cell phones.”
In the 1980s, a survey might have achieved a 70 percent response rate, whereas in 2016 the response rate to phone surveys is just 0.9 percent, according to data compiled by Wired.com.
But Zinman says that doesn't mean the average poll is systematically skewed or erroneous.
"Overall polls are very accurate and the industry has found ways to adapt to the changing technology and demographic changes within society," he said. “It’s challenging for the industry and it’s expensive to make all those dead end phone calls. But if you look at 2012, the results are still pretty darn accurate.”
A current average from Real Clear Politics shows Clinton leading Trump in Michigan by seven percent. While Clinton has yet to trail Trump in Michigan, Republicans remain adamant the state is "in play" to be a potential toss up in November.
Voters in Michigan have not elected a Republican president since 1988.
Electoral maps based on current polling from FOX News and NBC News categorize Michigan as "leaning Democrat," while CNN categorizes Michigan as "solidly Democrat." A classification for Michigan from FiveThirtyEight, which takes into account polling averages, and economic, demographic and historical data, closely resembles CNN's prediction.
However, Real Clear Politics still categorizes Michigan as a "toss up," based solely on averaging recent polling data.
Zinman said Michigan should be considered as an "almost-swing state."
"It's the kind of state that, for a Republican to be genuinely competitive here, the candidate would have to fundamentally change the national equilibrium of the race in order for Michigan to be in play," he said.
The last time Michigan was genuinely a swing state was in 2004 when Bush was re-elected, Zinman said. While he went on to win the election, George W. Bush aggressively campaigned and ran ads in Michigan but lost the state by 3 percentage points.