Collective Wisdom from the Experts 137
Once they are ready to give their initial estimate, they each write their indi-
vidual figure on a card. When everyone has finished, on the count of three
they all hold up their cards.
Now we see how they compare. If they are very close, we go with the more con-
servative number. If there is a wide discrepancy, we ask the developers to talk
about the assumptions that went into their estimate. After more discussion, we
ask them to estimate again. What happens most frequently is that the estimates
converge to a single number as the developers gain a common understanding
and agreement on what will be required to complete the feature.
This approach is advantageous because:
• All of the team is involved in coming up with the estimates and all varying
perspectives are shared. Often team members are all of one mind and can
get to a shared estimate quickly.
• Later, when actual coding begins, developers have all been exposed to the
thought process that went into the estimates, making it less necessary that
only certain people can work on any single feature.
• By having the team “own” the estimate, there is less chance of backlash.
Their estimate may still be wrong, but team members will be less confron-
tational about it and more cooperative in coming to a revised estimate.Remember, the best estimators are those who will do the work.