Black swan events
Clip: Season 2 | 3m 3s
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.
Aired: 09/06/12
Expired: 09/07/17
Clip: Season 2 | 3m 3s
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.
Aired: 09/06/12
Expired: 09/07/17
