When Estimates Change the Design

1. An Estimate That Changes Nothing Was Wasted

The previous lessons argued that estimates are for deciding, not for demonstrating. This one shows it, by working four cases where a single number removes an option that was otherwise perfectly reasonable.

Each case has the same shape, and that shape is the part you can carry to other problems.

1. A design is proposed and sounds plausible.
2. One quantity is estimated, roughly, in under a minute.
3. The result is not close. It is off by an order of magnitude.
4. The design is eliminated, and what replaces it follows from the same number.