Cone of Uncertainty
The range of an effort estimate is widest at the start of a project and narrows only as understanding grows.
The cone of uncertainty describes how every estimate carries its largest margin of error at the start of a project — exactly when the least is known about the problem. With every clarified requirement and every architecture decision made, the range narrows. Anyone who commits to an effort figure without that clarification is estimating at the widest point of the cone: guessing early and paying late. The term makes visible why “quick to build” at the outset says nothing about the effort — only about missing understanding.
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