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What Is The Point In Estimating?

by Kelly Waters, 10 December 2007 | Agile Estimating, Agile Planning

Agile development - estimating using fibonacci numbers as pointsOne technique used by agile development teams is the idea of estimating product features using points. This has a few distinct advantages over estimating in physical units of time.

1. Estimating is very quick because it’s an intuitive estimate of a feature’s size.

2. An estimate in points indicates a feature’s size relative to another, and does not give the illusion of being precise.

3. Over time, and using consistent iterations (e.g. 2-week sprints), you get a strong feel for how many points a team can deliver in an iteration. Even if a team is bad at estimating, as long as they’re consistently bad, this makes a team’s commitments self-correcting.

Some agile teams use Fibonacci numbers to do this. Fibonacci numbers are a sequence where each number is the sum of the previous two, i.e:

1, 2, 3, 5, 8, 13, 21 …

Using Fibonacci adds an element of science to the concept of estimating using points, adding the laws of distribution as a dimension.

If you’re interested in understanding more about the scientific background of Fibonacci numbers – which weren’t invented for agile development by the way! – you might be interested to listen to this Radio 4 podcast on Fibonacci

Kelly.

See also:
How to estimate your product backlog

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One Response to “What Is The Point In Estimating?”

  1. David O'Br says:

    That is fantastic, we use a similar strategy! For us the Brun–Titchmarsh theorem of progressive primes, to help make Agile intuitive and simple for the whole team.

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