Here is my A Day Without Women post, titled A Day Without Hillary:
Most decisively, there was a sudden change in the net sentiment results that followed immediately after FBI Director James Comey released his Oct. 28 letter to Congress about a renewed investigation of Clinton emails. Immediately afterwards, there was a 17-point drop in net sentiment for Clinton, and an 11-point rise for Trump, enough for the two candidates to switch places in the rankings, with Clinton in more negative territory than Trump. At a time when opinion polling showed perhaps a 2-point decline in the margin for Clinton, this conversation data suggests a 28-point change in the word of mouth “standings.” The change in word of mouth favorability metric was stunning, and much greater than the traditional opinion polling revealed.
Based on this finding, it is our conclusion that the Comey letter, 11 days before the election, was the precipitating event behind Clinton’s loss, despite the letter being effectively retracted less than a week later. In such a close election, there may have been dozens of factors whose absence would have reversed the outcome, such as the influence campaign of the Russian government as detailed by US intelligence services. But the sudden change in the political conversation after the Comey letter suggest it was the single, most indispensable factor in the surprise election result.
This conclusion helps us to understand how it is possible that the polls were generally correct about a Clinton lead through most of the campaign, but nevertheless Trump still won because of a late October surprise.
I’m not sure to what degree I should trust Engagement Labs’ chief commercial officer, and this same fellow acknowledges that in elections this close any number of factors in concert can influence results; but that’s the point too. The Comey letter came at the right moment.