The Role of Chance in US Presidential Elections

The San Diego Wet Lab is hosting a political science lecture on Tuesday March 7th from 630pm – 730pm at the La Jolla Riford Library.  David Forney, MIT PhD, from the San Diego Wet Lab will discuss the policies and mechanisms responsible for the difference between the popular vote and the electoral vote, as well as how the electoral college amplifies noise from the polls.


Electoral vote margins in US presidential elections tend to vary widely from popular vote margins.  The 2016 election however, appears as an outlier compared to all other elections from past 100 years. To understand the factors driving this variance, historical data from the National Archives was used to quantify the effects of three policies on the observed variance between the electoral and popular vote. Results indicate that these policies and the various mechanisms that derive from them explain 96% of the variance.  Random noise contributing to narrow state victories has the largest effect, resulting in about 37% of the observed variance in electoral vote – enough to swing victory from one candidate to another.  Furthermore I find a gap growing between left and right that may lead to more discrepancies between popular vote and electoral vote in the future.

This event is part of the San Diego Wetlab’s citizen science lecture series held every first Tuesday at 6:30pm at the La Jolla Library and every third Thursday at 6:30pm at the Downtown Library.   Please check the San Diego library system events page for location details and changes in the upcoming schedule.