from hbr.org/2014/12/your-agile-project-needs-a-budget-not-an-estimate

Nearly every software development project starts with one question: How much is this going to cost?

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Maybe it’s been asked another way — How long will this take? How many stories can we get into this next sprint? How many people do we need to hire to get this done? How much money do I we need to raise?

These are all variations on the same question — how much effort is this going to cost in terms of time and/or money?

There are two common replies to this question: 

1. We don’t know;
2. Let us estimate and get back to you.

Stakeholders and decision-makers don’t like the first reply because they desperately need an answer to their question and they don’t have the knowledge to answer it themselves. Technical teams don’t like the second answer, because estimating takes a ton of time and it’s often abused

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To minimize the risk of having your next technical project go awry, stop estimating and start budgeting.

For most strategic decisions, estimating is too precise.

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tactical approach to budgeting. [update throughout the life of your project]

Step 1: Identify Decisions
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Step 2: Match Precision to Decision
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Step 3: Budget