Estimating and contingency

An estimate is a claim about an uncertain future. Most organizations treat it as a commitment made by whoever said the number, which is why estimates are padded, disbelieved, and padded again.

Decompose before you estimate

Estimate the work, not the project. Break it down until each piece is small enough that someone who would do it can picture doing it — usually a week or two of effort. Below that you are estimating noise; above it you are guessing.

Two decomposition failures are worth naming. Missing scope is the larger one: integration, data migration, environments, testing, documentation, training, and the coordination overhead of everyone involved routinely go unestimated because nobody owns them. Double-counted contingency is the other: padding inside every task, then adding a reserve on top of the padded total.

Pick the method that matches what you know