What is the wisdom of the crowds? The Plymouth experiment by Francis Galton

In the year 1906, Sir Francis Galton, a polymath, once visited a farmers’ fair in Plymouth, south of Boston. Much like the present-day fair, there was kind of a lottery contest held. Around 800 people had visited the fair that day. Galton was intrigued by this lottery contest.

The task was to guess the correct weight of the big ox being butchered. Anybody who guessed the closest weight would be rewarded. All contestants were to write their guesses on tickets. Later that day, Galton ran a check on the tickets and found something astonishing.

Let us talk about the most popular TV show ‘ Who wants to be a millionaire’. To be a millionaire, you have to answer 15 multiple-choice questions correctly. One of the lifelines offered to the candidate involves asking the audience for the correct answer through a poll. Out of the four options allotted to the question, the one with the maximum votes is selected as the final answer.

There was another experiment conducted in 1987 by an American Economist, Jack Treynor. This time there was no ox but 850 jelly beans in a jar and 56 participants. You are right. The participants had to guess the number of jelly beans. The result was remarkable.

The Plymouth experiment concluded that the mob of 800 people as a whole guessed the closest weight. The crowd guessed even better than a group of cattle experts or farmers! In the millionaire show, 95 percent of the time, the audience is correct. Jack Treynor concluded that the error in estimate by the 56 participants was not more than 2.5 percent.

Would you conclude that a crowd is wiser than a group of experts? Or would you conclude that a crowd as a whole is always correct in guesses and predictions?

You might have already guessed how the crowd wisdom works. A bunch of overestimates, when they come together with underestimates, the biases seem to cancel out each other. I would opine that it is a statistical result, not a universal law.

The wisdom of the crowds can also be a possible explanation of how an English mentalist Derren Brown win lotteries and make correct guesses.

When will the wisdom of the crowds work?

1. The people involved in the crowd must be diverse. Diversity is better than similarity here.
2. An individual answer must not be biased. It must come out independently.

Let us talk about diversity first. By diversity, I do not mean people from a different religion or cultural background. Diversity is rewarding when opinions are diverse. This is to say that a group of diverse opinions will prove to be more accurate than similar opinions. The Plymouth experiment is evidence of this. If you bring in too many overestimates or underestimates, the performance of the group will surely deteriorate.

Independence is a must. If I pay too much heed to what you think about my friend, I may start behaving differently towards him. This is called bias. If you predict more heads than tails in a series of coin tosses, you are biased. If your opinions can influence mine, ironically, we can’t make a good team for Plymouth! Should I even mention the mad holocaust caused due to a common belief that Jews are horrible people?

Is democracy of thought always correct?

I will leave that to you to answer down in the comment.

Where does the wisdom of the crowds fail?

Of course, a crowd is not extraordinary. To make extraordinary decisions, you need an extraordinary person. For instance, you are planning to go on a tour with your family. Alas! You are not able to come into agreement with their opinions. Your mom wants to travel to a hill station, your dad to the south pole, your brother to a coastal area, whereas you want to tour in the middle of nowhere!

This results in you choosing a place that is least hated by you and your family. The same thing applies to have something special for dinner tonight. Keep in mind that a crowd votes for an individual, which it hates the least.

When it comes to having a creative outlook, a crowd’s wisdom is always the worst. A bunch of creative people will always think of extremities. Normalcy is boring. You cannot rely on the wisdom of the crowds when creativity is needed.

Crowd selection is vital. If you select a team of cricketers to guess a patient’s problem, the wisdom is as useless as your appendix! However, if you mix several health experts to make guesses, we will probably make dead Galton smile.

Indeed, it is all a question of how you select your team and use the wisdom of the crowds.

A crowd is smarter, but not all the time.

Originally published at https://www.yashkedia.com on October 8, 2020.