How Accurate Are Early Presidential Polls?

With her campaign for the Democratic nomination for president barely a month old, a new poll finds Hillary Clinton's numbers among voters improving, according to The New York Times. Her favorability ratings are higher than they were earlier this year, with about 48 percent of those polled deeming her "trustworthy," even though Clinton has faced questions about her email servers and over tax and donor issues with the Clinton Foundation. The poll also found that Clinton's husband, former president Bill Clinton, is still very popular among Democrats, with 76 percent expressing a positive view of him. And, Democrats polled seem to be OK with the idea that Bill would have influence in a new Clinton administration headed by his wife. But is it too early too put much stock in such polls?

At this point, only one other Democrat, Bernie Sanders of Vermont, has launched a campaign, and the election is still 18 months away. Back in 2006, a similar New York Times poll had Clinton and former New York City mayor Rudy Giuliani as front-runners for their parties' nominations for the 2008 race (interesting to note that Clinton was referred to as "polarizing" in both Tuesday's poll, and the 2006 article, for whatever that's worth). That 2006 poll had then-Sen. Barack Obama in second, and former Sen. John Edwards third.

We know how 2008 turned out; Clinton and Obama battled until late in the primaries before she conceded. And Edwards, who had been John Kerry's running mate for his unsuccessful presidential bid in 2004, was later indicted on charges he used campaign funds to cover up an extramarital affair (he was convicted on only one charge). Giuliani eventually quit the 2008 race to endorse Arizona Sen. John McCain, the GOP nominee that year.

So, how accurate are early polls? Not very, according to a study by the Pew Research Center, which finds that polls to determine who will win the White House that test voters too early usually produce incorrect results. But, the Pew study found, such early polls might offer a snapshot of voter sentiment, even though they're not as reliable for predicting the outcome of a presidential race.

For instance, the Pew report found that early 1999 polls correctly predicted then vice-president Al Gore would be the Democrats' nominee in 2000, and that Republicans would choose George W. Bush. However, early polls in 1991 predicted former New York Gov. Mario Cuomo would be the Democratic contender in 1992, but of course, that year was all about Bill Clinton (Cuomo, who died earlier this year at 82, never ran for president).

So while Clinton's campaign seems to have weathered some early controversies without taking too much damage, if past polls are any indication, it's probably way too soon for her to feel too confident yet.

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