One of the more popular ideas to emerge from research on group decision-making (especially under the brand "collective intelligence") is known as the "wisdom of crowds." This is a mathematical guarantee that the average belief in a group of people is more accurate than the belief of an average individual (really).

Beliefs in this context mean estimates such as "how many people currently support our campaign. and forecasts, such as "how many people will vote for us". Beliefs might also be categorical, such as "which candidate will win this campaign."

Here are some more examples of things a group might estimate or forecast:

• How many jellybeans are in this jar?
• How long will this project take to complete?
• How many units of this product will sell next year?
• How many volunteers will we be able to recruit?
• Which candidate will win the election?
• Will oil prices exceed $200/barrel before end of 2026?
• Will Andy Burnham be prime minister on Dec 31, 2027?

Honestly, you can apply this practice without any further instruction from me: simply ask a lot of people the same question, and take an average. A fair bit of evidence suggests that the average will be pretty accurate. This is known as a "prediction poll."

You can also see this principle widely applied in prediction markets, also known as betting markets. In these markets, people place bets on future outcomes and earn money if they are correct. They are called "markets" because they operate on a similar principle to the stock market.

Prediction markets and prediction polls are methods for crowdsourcing accuracy — asking people outside your group to provide input, so you can come up with accurate beliefs.

Sometimes, however, not only care about generating a specific forecast or estimate, but instead might care about supporting the formation of accurate beliefs within your own group. Indeed, if you have a group making a decision together, it is inherently desirable that their decision be based on an accurate understanding of the world!

Unfortunately, scientific research shows that lots of things happen in groups that can lead outcomes to depart from the simple average. When we talk to each other around a table, dominant voices can undermine group accuracy, leading to the "wisdom of the few" instead of the wisdom of the crowds.

By thinking about the ways in which groups can form accurate beliefs and the ways in which groups can go wrong, you can better design your facilitation practice to support the wisdom of crowds.