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Should you trust unanimous decisions? - Derek Abbott

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TEDEd Animation

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Imagine a police lineup where ten witnesses are asked to identify a bank robber they glimpsed fleeing the scene. If six of them pick the same person, there’s a good chance that’s the culprit. And if all ten do, you might think the case is rock solid. But sometimes, the closer you start to get to total agreement, the less reliable the result becomes. Derek Abbott explains the paradox of unanimity.

Consider a hostage situation where a crazed gunman kept 20 peopled detained in a house for a whole week. His face was on full view for a week. The hostages eventually go free and the gunman escapes. Later the police capture a person who they think is the gunman. During an identity parade all 20 former hostages agree that the police have caught the correct man. What is the likelihood the police were correct?

About TED-Ed Animations

TED-Ed Animations feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed Animation? Nominate yourself here »

Meet The Creators

  • Educator Derek Abbott
  • Script Editor Alex Gendler
  • Director Brett Underhill
  • Animator Brett Underhill
  • Narrator Addison Anderson

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