One of the many stories to emerge from the raucous 2016 presidential primary season centered on the concept of momentum: who had it, who didn鈥檛, and what it all meant for primary outcomes. Did racking up a series of early wins make voters in later primaries more likely to shift their support to the early winners? And if so, could the party鈥檚 nomination have gone to a different candidate if different states had voted sooner?
New research by, Jon and Abby Winkelreid Professor of Political Science, suggests that the answer is no.
The results of this study, 鈥�,鈥� has just been published in the. Vanderbilt graduate students Andrew Engelhardt and Marc Trussler co-authored the peer-reviewed research.
鈥淒uring the 2016 election, the word 鈥榤omentum鈥� was often used to predict or explain the outcome of a primary election, but it was never really clear whether voters were actually casting votes based on a candidate鈥檚 previous performance,鈥� Clinton said. 鈥淒espite the term being used so often, we wanted to see if voters were changing their votes to support winners. Were New Hampshire voters really more likely to support the candidate who won the Iowa caucuses simply because that candidate won? Or were voters making their decisions based on the candidate they liked best?鈥�
To answer this question, the researchers mined a huge trove of survey data鈥攎ore than 325,000 interviews, or nearly 1,700 per day鈥攃ollected nearly every day starting in December of 2015 and continuing throughout the 2016 primary election using NBC 狐狸视频/SurveyMonkey tracking polls that they helped write. The unprecedented size and scope of the data allowed them to track candidates鈥� support throughout the primary season for a demographically balanced sample of the U.S. electorate.
To measure whether voters were more likely to change their mind to support winning candidates, the researchers compared the support for each candidate before and after each state primary to the day-to-day variation in support that occurred in the absence of primary election events.
鈥淚f winning a primary created momentum among voters, we would expect to see a sizable fraction of voters鈥� changing their mind and supporting the winning candidate after each primary,鈥� Clinton explained. 鈥淏ut in almost every case, the shifts we see are largely indistinguishable from the ordinary ebb and flow we observe in public opinion.鈥�
The researchers also looked at whether other primary events such as debates were able to change voters鈥� minds. 鈥淲e again found no evidence that voters were reacting to debate performances during the time period we examined,鈥� Clinton said. 鈥淏y the time of the Iowa caucuses, most voters seemed to have a good sense of who they supported. Voters were not supporting candidates because they were winning.鈥�
When candidates did win several primaries in a row, Clinton said, the reason was usually because those states had similar electorates, not because the voters in later primaries were drawn to winning candidates. And when a candidate did start to win a greater percentage of the vote, he said, it was because other candidates had dropped out and the field was smaller.
Clinton cautioned that his findings don鈥檛 mean that staggered state primaries don鈥檛 make a difference. Early performance can and does impact fundraising and media attention鈥揻actors that certainly allow a candidate the ability to keep campaigning.聽 鈥淏ut, at least in 2016, we don’t see a whole lot of evidence that voters were changing their support based on who won,鈥� he said.
鈥淭he fact that California is voting on Super Tuesday in 2020 may indeed have large consequences for the ability of candidates to remain viable, but our research suggests that its outcome is unlikely to be impacted by who won South Carolina two weeks before,鈥� he said. 鈥淰oters make decisions based on who is running, not who is winning.鈥�