Showing group wisdom with jelly beans counting

There was an internal Project Managers communication session yesterday where about 250 of them turned up. My 10 minutes message was to introduce the upcoming Project Management CoP. In a request for my segment to be more interactive, I ran a Jelly Beans Counting Contest with the help of my colleagues to drive home a message on group wisdom. Something which I came across in James Surowiecki's Wisdom of Crowds.

The preparation involves sourcing for a nice enough jar and above-the-mark jelly beans. Then I went on to count the jelly beans and tried my very best to keep the numbers to myself (it's 420 actually). To show the PMs on what this is all about, I did up a quick poster with the text "Count the Jelly Beans Contest... Person with the closest answer gets to keep them all!". My colleagues and I went on to setup the counting station across the registration table.

When the registration began, the counter staff didn't seem to be very successful in channeling the PMs to the counting station. My colleague then suggested to shift the station beside the entrance of the function room. True enough, we were able to rally more participation since we were in their way of passage.

We managed to get a total of 67 participants. Here is what we found:

• Mean: 1000.313 (since there are those who guesses 10,000 and the other 20,000)
• Median: 395
• Closest guess: 418

Since the median score is 25 away less then the actual, I was curious to find out the who guessed within 395 and 445 (25 more than actual) and it turns out than only 4 of them guessed within that range. This implies that 94% of guesses did worse than the median score. The audience looked surprised when I shared this with them.

The point which I brought across to the PMs is this...

There are times when the answer to a problem isn't that obvious, and we need to come together and learn with each other.

This is something we don't always do, but the person who guessed 1000 jelly beans did really think that there are that many jelly beans in there, and this can translate to some kind of disaster or poor quality when applied to real work situations. A PM CoP thus forms the social fabric where the Project Managers can come together in situations like this.

But there are a few things to note for group wisdom to work here:

• Everyone should have local knowledge and use that to determine the best solution (guess) without being affected by others.
• Decide on an effective way to aggregate the groups inputs (in this case, the median far surpasses the mean). In actual situations, this require the team to decide on the most effective way.