Do undecided voters break for the challenger?

FAQ Incumbent Rule Legacy blog posts

When pollsters interpret results for a race involving an incumbent, most are at least aware of a phenomenon observed for telephone surveys over the last 20 or 30 years: Voters who are still undecided on the very last poll tend to “break” disproportionately for the challenger. The two most important posts on this subject are the following:

Also, click on this link to display short excerpts of all of the posts concerning the incumbent rule in reverse chronological order (most recent first).

Mark Blumenthal

Mark Blumenthal is the principal at MysteryPollster, LLC. With decades of experience in polling using traditional and innovative online methods, he is uniquely positioned to advise survey researchers, progressive organizations and candidates and the public at-large on how to adapt to polling’s ongoing reinvention. He was previously head of election polling at SurveyMonkey, senior polling editor for The Huffington Post, co-founder of Pollster.com and a long-time campaign consultant who conducted and analyzed political polls and focus groups for Democratic party candidates.