Depends on who I'm talking to. An estimate is not actually a number, it's a probability distribution. Few people want to hear that; they want one number to summ

Depends on who I'm talking to. An estimate is not actually a number, it's a probability distribution. Few people want to hear that; they want one number to summarize it. But not everyone wants the same number. My team wants to know the mean; my manager needs to know where the cumulative distribution reaches 90%; and marketing needs to know where the cumulative distribution reaches 99%. In my experience, a developer's educated guess hits very close to the median completion time. Software task completion tends to be lognormally distributed, so to get the appropriate scaling factors, multiply that educated guess by 1.6, 5, or 10 respectively.