There’s so many good presentations happening now and Monday was another one called Estimating: The Sociological Effects in a Group. Great talk by Todd Williams who specializes in rescuing failing projects. There were two big takeaways for me:
Statistically, the time to complete a task will be less than your original estimate only 50% of the time. The other 50% you’ll be over. If you estimate a number of tasks, such as at the start of a sprint, you’ll average out to roughly the sum of all your estimates.
This ties in with the second, more important takeaway which is that most people treat estimates as quotes. As the consequences become more serious for the accuracy of their estimate then they’ll increase their estimate to make sure they can “hit the number.” The problem with this is the student syndrome where a person doesn’t tackle the task until the last moment, burning up any padding in the estimate and expanding the schedule for the whole job.
To prevent this from happening Todd recommended the Agile practice of short iterations and also cautioned project managers about treating estimates as quotes.