When you bring a lot of estimates together, you are likely to have a final result where the average over time is close to the historical average. One example of this is driving to work. If you were asked to plan how long it would take to get to every stoplight on the way to work exactly, this would be impossible. But you have a pretty good idea what time you need to leave home each day to arrive at work at the right time.
Related articles
- Regression toward the mean (wikipedia.org)
