Comparison
Iron trianglevsScope creep
Iron triangle
the date was fixed and the scope was fixed, and everyone acted surprised about quality.
Scope, time and cost are related, so fixing all three fixes quality as the thing that gives. It is a crude model and it remains the fastest way to have an honest conversation with a stakeholder who wants all three. The engineering contribution is to name which variable is actually moving, because when nobody names it the answer defaults to quality and nobody has to admit it.
Full entry →Scope creep
each addition was reasonable on its own and the project is four months longer than it was in January.
The gradual expansion of what is being built without a corresponding change to time or resources. It is rarely one decision, which is what makes it hard to push back on: no individual request is unreasonable and none of them are counted. The defence is arithmetic rather than refusal — accept the change and state the consequence in the same sentence, so that the tradeoff is made by whoever owns it.
Full entry →