For the best round-up of the latest wonkage on the topic of the influence of the presidential debates on polling and presidential elections, you probably can’t do much better than Dylan Mathews’ post, “Do presidential debates usually matter? Political scientists say no” at Ezra Klein’s Wonkblog.
Matthews quotes conclusions from a handful of statistical studies and he trots out five flashy charts measuring the effects of the debates and media framing. Among his conclusions:
…History is littered with examples of debate performances that allegedly decided elections. There was John F. Kennedy beating Richard Nixon due to the latter’s not-ready-for-prime-time scruff. There was Gerald Ford losing after asserting that the Soviet Union didn’t dominate Eastern Europe. There was Ronald Reagan’s “there you go again” comeback to Jimmy Carter, and Lloyd Bensten’s admonition that Dan Quayle is “no Jack Kennedy.”
But did any of those actually matter? The best political science says no.
Matthews adds, “Perhaps the most compelling evidence for the irrelevance of debates is that polling in past races hasn’t changed much at all following them” and he depicts the impressive before and after “continuity” in a tightly lined-up diagonal graph from a study by Columbia University’s Robert Erikson and Temple’s Christopher Wlezien. Matthews also shows Nate Silver’s chart indicating “slight national poll gains for challengers following debates” and adds,
However, the effect is small, with an average shift of 2.3 percentage points, and it’s hard to infer causality with such a small sample. In any case, only two elections — 1980 and 2000 — saw the candidates trade places in the polls following the debate, and in every case the poll leader after the first debate won the electoral college. So Obama can rest easy assuming he still leads after tonight.
Matthews reiterates, “The evidence for debate effects on election outcomes is thus weak at best, and at worst nonexistent.” But, interestingly, Mathews cites four different studies which indicate that “The media seems to be the far more important player” than even the candidates themselves in deciding voters’ opinions about the debates. He notes other studies indicating measurable effects of debate-viewers being exposed to conversations and opinions of other viewers, and yes, even social network buzz.
If Matthews is right, whatever polling differences emerge following the debates may be better explained by peer influence and media spin than the quality of performances by President Obama and Governor Romney.