there is no way to predict how the polls will react to the news that the f.b.i. found an email cache that has prompted another look into hillary clinton <u+2019>s email practices. we won<u+2019>t know for a few days. but as we wait for more data, it<u+2019>s worth remembering all of the big news events this year, and what came of them: many moved the polls, but none fundamentally reshaped the race. the f.b.i. director, james comey, excoriated mrs. clinton in july for using a private email server while she was secretary of state. her opponent, donald j. trump , was accused of sexual assault by around a dozen women after a video revealed him bragging about grabbing women and getting away with it because he was a celebrity. and then there were all of the other episodes along the way: capt. humayun khan , alicia machado , judge gonzalo curie l , mrs. clinton<u+2019>s pneumonia-related collapse , her comments about <u+201c> deplorables ,<u+201d> three presidential debates and two political conventions. many of these events seemed to have a discernible effect on the polls. mrs. clinton<u+2019>s numbers slipped in early july, after mr. comey announced he would bring no charges over her email practices yet criticized her use of a private email server. mr. trump<u+2019>s numbers slipped after the conventions and after his feud with the parents of captain khan, who was killed while serving in iraq. some of these events seemed as if they could be true turning points <u+2014> moments that permanently shifted the race. just a few weeks ago, it was considered a distinct possibility that the video of mr. trump, the subsequent allegations against him and the quick abandonment of some republican officials could open the door to a landslide, dragging down not just mr. trump but also the entire republican party. indeed, the polls shortly thereafter showed mrs. clinton taking a considerable lead. yet here we are, again in a somewhat tighter contest and prepared for yet another swing in the polls. the polls this year have followed a pretty consistent pattern. mrs. clinton<u+2019>s lead has bobbed up and down between two and eight percentage points, depending on the latest news. when things go well for mrs. clinton <u+2014> or poorly for mr. trump <u+2014> she surges into the mid-40s, and mr. trump dips a bit into the upper 30s. when things go well for mr. trump <u+2014> or poorly for mrs. clinton <u+2014> she falls back into the lower 40s and he gets around 40 percent. these oscillations are more pronounced than in recent elections. that<u+2019>s probably because there are so many voters who are dissatisfied with both candidates, or because voters are torn between party loyalties and the demographic appeals of the candidates. many of these dissatisfied voters are extremely likely to vote for one candidate or another, but they are not happy about it. when the news isn<u+2019>t so good for the candidate they<u+2019>re likelier to support, they say they<u+2019>re <u+201c>undecided<u+201d> rather than bring themselves to admit <u+2014> either to themselves or to the polling interviewer <u+2014> that they<u+2019>ll support their candidate. these same swings in enthusiasm have an effect on whether pollsters judge them to be likely voters, or even the propensity for voters to respond to surveys at all. this theory helps explain why the most abrupt movements in the polls seem to come when the race is near one of its two extremes. mrs. clinton surged after the first presidential debate in part because she was near her low point heading into it. the allegations about mr. trump<u+2019>s sexual misconduct didn<u+2019>t hurt him as much in the polls as his first debate performance, for instance, because mrs. clinton<u+2019>s marginal supporters had already flocked back to her column after the debate. there were fewer voters for her to lure back. with this history in mind, it would make sense if the newest f.b.i. revelations took a modest toll on mrs. clinton<u+2019>s standing in the polls. mr. trump<u+2019>s position has improved over the last week or so, but he still trailed in national polls by about five or six points before friday, when news of mr. comey<u+2019>s letter to congress about the new emails surfaced. there<u+2019>s room for mrs. clinton<u+2019>s standing to fall a bit, or perhaps for mr. trump to continue to consolidate republican voters. but the same history makes it harder to argue that a change in the polls would represent a lasting shift in the race. if most of the movement in the polls can be attributed to varying degrees of enthusiasm among voters at the periphery of each candidate<u+2019>s coalition, then the polls might move without any real change in the underlying race at all. to be clear, this is not to say that mr. trump can<u+2019>t win, or that shifts in the polls can<u+2019>t reflect a significant underlying shift in voter sentiment. it<u+2019>s possible that variations in enthusiasm really do correlate, for instance, with the willingness of voters to turn out. one can imagine the perfect storm: democratic-leaning voters, newly dispirited by the news about mrs. clinton<u+2019>s emails, decide not to turn out; well-educated, republican-leaning white voters return to their traditional party after a few weeks of relative quiet from mr. trump and bad news about mrs. clinton; undecided, democratic-leaning white working-class men break for mr. trump; hispanic and black turnout falls short of expectations, and so on. but so far this cycle, it has been safer to bet that the polls will return to where they<u+2019>ve been than to assume that a new shift will be a lasting one. it points toward a clear, fundamental dynamic in the race: a majority of voters dislike both candidates and they would prefer not to vote for either one of them, but they believe mr. trump is not fit to be president. the upshot provides news, analysis and graphics about politics, policy and everyday life. follow us on facebook and twitter . sign up for our newsletter. a version of this article appears in print on november 1, 2016, on page a20 of the new york edition with the headline: another swing in the polls perhaps, but not necessarily a shift in the race. order reprints | today's paper | subscribe
get ready for another swing in the polls, but not necessarily a shift in the race
nate cohn