Yesterday, infamous pundit and recreational politician Sarah Palin announced that she will not, after all, be running for president in 2012. (No link; it would only encourage her.) This news, fittingly, emerged on the same day as rumors that in the event the McCain campaign won, they had actually considered not swearing Palin in. That should give some picture of just how terrible a vice presidential candidate she was. But assume the rumors are unfounded—are there numbers that document her toll on the 2008 campaign?
Yes. A 2010 paper by Roy Elis and Norman Nie of Stanford and D. Sunshine Hillygus of Duke confirms that Palin was not just garden-variety bad; she was downright dreadful—actually a liability to the McCain campaign. Vice presidential candidates usually have a negligible impact on presidential tickets, making that finding somewhat extraordinary. The research buttresses similar work by Richard Johnston and Emily Thorson, which found that in 2008, no other factor more than Palin’s approval rating “moved McCain support with such precision.” And her impact, as Elis, Nie, and Hillygus find, was substantial. Examining the fluctuation of Palin–approval between September 2008 (just after she joined the ticket) and Election Day, they find that 34 percent of respondents “downgraded” their views of Palin, and only 12 percent became more favorably inclined toward her. Testing that overall polling against a counterfactual situation in which views of Palin remained frozen at September levels, the scholars found that she accounted for a nearly 2 percent drop in McCain’s vote share on Election Day. It’s somehow reassuring to know that in addition to every other way in which Palin made a ghastly vice presidential pick, she was electorally unwise to boot.