Timing: 10 mins
- A good-sized audience – 10 or more (the bigger the better)
- Pens & paper for all
It is best to sneak this exercise in when it is least expected.
Start by selecting something in the room that is not easily counted or estimated. Take the time to write the exact number down and hide it from the audience.
Then, have each individual quickly and privately write down their own estimate.
Gather all of the estimates and calculate the average.
Cross your fingers and unveil the number that you wrote down earlier. It should be relatively close to the group average.
I have done similar exercises about a dozen or so times and the results are usually spot on. However, there is always a chance that the results could be off, so always make sure to start by announcing that you want to perform an experiment together. Participants will understand if the results are not perfect.
Some things you can use to estimate:
- Your weight – although people tend to be generous and the estimates are usually low.
- Number of books available on Amazon.com
- Number of words on a page – I’ve had the most success with this one. In a class environment, I’ll use the lab write-up and have the students write their estimate on the back.
- Number of steps it takes to walk from one side of the room to the other – this one is fun, but you could get accused of rigging the outcome.
- Balloons in the room – only works if you played the 99 Test Balloons game earlier.
- Please leave a comment to share some of your ideas and experiences.
Other helpful hints:
- To keep things quick, open a spread sheet to type in everybody’s estimate as they show them to you. This also makes it easy to calculate the average in front of everybody.
- Analyze the data with the class. You will likely get a very wide variance. I often find that no one individual estimate is as close as the average. This speaks to the true wisdom of the crowd and of the importance of diversity.
- To make it even more interesting, give a prize to whomever had the most accurate estimate.
- The accuracy of the group estimate is usually stronger than any one individual’s.
- The larger and more diverse the crowd is, the better the estimate.
- Agile embraces this principle by involving the whole team in estimating and planning and by encouraging the creation of cross-functional teams.
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