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NEED TO KNOW

Black swan events

  • Aired: 09/07/2012
  • 03:03
  • Expires: 09/07/2017
  • Rating: NR
Need to Know's Jeff Greenfield explains how so-called "black swan" events sometimes have the power to swing U.S. presidential elections one way or another.
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Black swan events
What is the 'black swan' theory and how has it impacted U.S. elections?
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