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NOVA ScienceNOW

Wisdom of the Crowds

  • Posted 06.25.08
  • NOVA scienceNOW

In the early 1900s, British scientist Sir Francis Galton thought he was proving the ignorance of the masses when he noted that no one got the right answer at a country-fair competition in which entrants were asked to guess the exact weight of an ox. What Galton failed to realize was that the median of all the guesses produced close to the right answer—and showed the "wisdom of the crowd."

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Transcript

WISDOM OF THE CROWDS

PBS Airdate: June 25, 2008

NEIL deGRASSE TYSON: In an election year, people might disagree about who makes the best candidate, but you don't hear much argument on the merits of democracy: that millions of average people can, together, make a wise decision.

It wasn't always so. In the early 20th century, this controversial Englishman, Sir Francis Galton, tried to statistically test whether mobs of common folk were capable of choosing well.

And, as our musical correspondent Rob Morsberger tells us, what Sir Francis actually found was that, mathematically, at least, there's often wisdom in a crowd.

ROB MORSBERGER (Correspondent): Sir Francis Galton was a nobleman

And scorned the common masses.

He thought that votes of governance

Should be left to higher classes.

He'd prove with all the data

From a contest inescapable,

Of guessing even simple things

That commoners were incapable.

CARNIVAL BARKER: Ladies and gentlemen, step right up.

ROB MORSBERGER: What kind of contest might it be?

CARNIVAL BARKER: Guess the ox's weight and see. Guess the weight correctly and win a prize!

LITTLE BOY IN CROWD: It's 100!

ROB MORSBERGER: Said a little one.

ADULT IN CROWD: That's much too light, at least a ton.

ROB MORSBERGER: An eager crowd queued up to play,

Eight hundred made a guess that day.

MATT WINTERS: So he had 800 data points.

CARNIVAL BARKER: And now the ox's weight is exactly...eleven hundred ninety-eight pounds. There are no winners!

CARNIVAL CROWD: Ohhhhhh!

ROB MORSBERGER: Sir Francis knew the rabble

Would never guess the weight.

How might they judge important things,

If left to meet that fate?

With mathematics he would show

How far they went astray.

But in the end his theory

Was in total disarray.

Because a curve of all the guesses...

ANDREW GELMAN: Oh that curve? It's the cumulative distribution function of the normal distribution.

Sorry, that's what it's called.

(The crowd laughs.)

ROB MORSBERGER: ...because graphing all the guesses

And determining their mean...

MATT WINTERS: I think he was talking about the median.

ROB MORSBERGER: And determining their me-dee-een.

He showed that if the crowd were one, its estimate is keen.

He showed that if the crowd were one, its estimate is keen.

JIMMY WALES (Founder, Wikipedia): Keen, yes.

ROB MORSBERGER: That's because, while no individual guessed the actual weight, the average of all the individual guesses is exactly right.

ANDREW GELMAN (Columbia University): The average will generally be better than a randomly selected individual guess.

ROB MORSBERGER: The average of the masses assures us of success.

MATT WINTER: I think he was talking about the median.

ROB MORSBERGER: And the larger the number of guesses we toss in...

MELISSA SCHWARTZBERG:...the more likely we are to get the right answer about the oxen.

ROB MORSBERGER: His premature prognostication,

They cannot help but scoff.

JENNIFER HILL: Galton should have gathered more data before he went shooting his mouth off.

ROB MORSBERGER: Sir Francis' hypothesis was rocked by ignoramuses.

He lost the proof he had avowed.

He found the wisdom of the crowds.

KELLY RADER: If you have a group of people and they each have tiny bits of information, then you can learn a lot, if we could just gather all those bits together.

ROB MORSBERGER: It's just like Wikipedia.

JIMMY WALES: Well, this isn't exactly like Wikipedia. It's a little bit different.

MATT WINTERS: It could maybe be Wikipedia. You don't even need to be an expert, but if you know something, then you're able to contribute, and that entry is able to be that much more informed.

ROB MORSBERGER: Another sample of this fare...

JENNIFER HILL: Who wants to be a millionaire?

REGIS PHILBIN IMPERSONATOR: Yeah, the audience lifeline.

JENNIFER HILL: If the person feels like they can't answer the question by themself, ask the audience.

KELLY RADER: The audience is right over 90 percent of the time.

JENNIFER HILL: There you go.

REGIS PHILBIN IMPERSONATOR: How 'bout that, Gelman?

ANREW GELMAN: The wrong Gelman...

REGIS PHILBIN IMPERSONATOR: Sorry.

ROB MORSBERGER: One by one we're not too smart,

But every guess it plays its part,

And when you add them up you'll find...

ROB MORSBERGER AND CROWD: The wisdom of the crowd.

Credits

Wisdom of the Crowds

Produced and Edited by
Vincent Liota

NOVA scienceNOW

Executive Producer
Samuel Fine
Executive Editor
Neil deGrasse Tyson
Senior Series Producer
Vincent Liota
Supervising Producers
Stephen Sweigart
Joey David
Editorial Producer
Julia Cort
Development Producer
Vinita Mehta
Senior Editor
David Chmura
Production Assistant
Fran Laks
Compositors
Brian Edgerton
Yunsik Noh
Music
Rob Morsberger
Associate Producers
Fran Laks
Molly Longstreth
Anthony Manupelli
Win Rosenfeld
Alison Snyder
Assistant Editor
Susan Perla
Camera
Jim Ball
James Callanan
Austin deBesche
Brian Dowley
Vincent Liota
Steve McCarthy
Sound Recordists
Bernie Beaudry
Lauretta Molitor
Roger Phenix
George Shafnacker
Tom Williams
Sound Mix
David Chmura
Animation
Sputnik Animation
James LaPlante
Brian Edgerton
Anthony Kraus
Yunsik Noh
"The Forgetting," Twin Cities Public Television
Production Manager For Crowd Segment
Candace White
Segment Production Assistants
Mona Damluji
Grisha Enikolopov
NOVA scienceNOW series animation
Edgeworx
Three dimensional brain animation
Courtesy Dr. Arthur W. Toga, Laboratory of Neuro Imaging at UCLA
Archival Material
ESA
Jet Propulsion Laboratory
Library of Congress
NASA
Special Thanks
Briarwood Healthcare and Rehabilitation Center, Needham, MA
Douglas Clowe
Bamidele Faboyede
Prasad Jayanti
Kimo Johnson
Eric Kee
Sue Moen
Soudan Underground Mine - A Minnesota State Park
Twin Cities Public Television
Jeff Woodward
Neil deGrasse Tyson
is director of the Hayden Planetarium in the Rose Center for Earth and Space at the American Museum of Natural History.
NOVA Series Graphics
yU + co.
NOVA Theme Music
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
Additional NOVA Theme Music
Ray Loring
Rob Morsberger
Post Production Online Editor
Spencer Gentry
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The Caption Center
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Eileen Campion
Lindsay de la Rigaudiere
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Paralegal
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Talent Relations
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Legal Counsel
Susan Rosen
Post Production Assistant
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Post Production Supervisor
Regina O'Toole
Post Production Editors
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Post Production Manager
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Compliance Manager
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Supervising Producer
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Business Manager
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Producers, Special Projects
Lisa Mirowitz
David Condon
Coordinating Producer
Laurie Cahalane
Senior Science Editor
Evan Hadingham
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Melanie Wallace
Managing Director
Alan Ritsko
Senior Executive Producer
Paula S. Apsell

This material is based upon work supported by the National Science Foundation under Grant No. 0638931. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

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Image credit: (math illustration) © WGBH Educational Foundation

Participants

Neil deGrasse Tyson
Astrophysicist, American Museum of Natural History
Andrew Gelman
Columbia University www.columbia.edu/cu/polisci/fac-bios/gelman/faculty.html
Jimmy Wales
Founder, Wikipedia en.wikipedia.org/wiki/Jimmy_Wales

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