Here’s a quick overview of two different perspectives on the current 2016 polling data and how it relates to the past election/s. If Hillary Clinton defeats Donald Trump on Tuesday night, it will mark only the second time in 64 years that one political party will control the presidency for more than two terms. The graph below shows how Clinton is faring in the most important races–those in the battleground states that have been close in the last decade–as she tries to achieve this feat of topping off a third consecutive term in power for the Democratic Party.
The race in 2008 was a (relative) landslide for Barack Obama. Even then, according to trend line averages from the HuffPost Pollster poll aggregation, Clinton’s current polling strength in North Carolina exceeds Obama’s small margin of victory in the state in 2008. Otherwise, the 2008 margin for Democrats is far above that in the two latter elections.
Comparing Obama’s actual margin of victory in 2012 to Clinton’s current polling position, the greatest disparities come from her relative underperformance in Iowa, Nevada, and Ohio. Virginia marks the only other state than North Carolina where Clinton has built on her predecessor’s success. The race is much tighter in a large majority of key battleground states this year for Clinton relative to earlier elections. That also lends credence to an important point Nate Silver made two days ago in explaining why his forecast model has proved so much less bullish on Clinton’s chances of winning the presidency.
Similar state-level results come up when comparing the final polling position of Obama in 2012 and now Clinton in 2016 (in battleground states). Note: the “final polling position” comes from the Democratic candidate margin based on Pollster’s trend line estimate/average.
The most meaningful examination will come when comparing these final polls to the actual 2016 vote, but still there are some interesting results here. Clinton is slated to do much better in Colorado than Obama was, even though Obama’s actual vote margin in the state–as seen in the first graph–came much closer to Clinton’s current polling position in 2016. A similar phenomenon seems to be occurring for Florida: Pollster’s trend line margin left Obama and Romney even (a margin of zero, explaining why no bar graph appears there), though Obama won by 0.88 percentage points–moving closer to Clinton’s current 1.7 point lead in Florida.
Unsurprisingly given the earlier analysis, Ohio, Iowa, and North Carolina show the biggest differences in the final state of the polls in 2012 and 2016. For the 2012 races in these states, the final poll trend line approximated the actual results fairly well. Perhaps that foreshadows Trump victories in Ohio and Iowa and a Clinton triumph in North Carolina. That’s at odds with my suspicion that Trump could retain North Carolina. While Pollster gives Clinton a 1.9 trend line lead, Trump and Clinton led two polls apiece and tied in another among the five most recent polls to be released. In the seven polls before that, Trump led three times, Clinton three as well, and the two candidates tied in another. Going back further gives you a more Clinton-friendly state of the race, but it’s much more of a mixed bag and up in the air at the moment than the 1.9 Clinton lead from Pollster would suggest.