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Scrum/Story points

Story points are a tool used to help with medium-term predictions as they may be needed for release planning or communication inside the organization. They also give a rough(!) sense of the evolution of team velocity. If these two are not needed, estimating in story-points is not adding any value.

Each story on the product backlog is compared to other stories to see how it's difficulty (representing the complexity of the work, time and effort needed for it and also the involved risk) compares. We typically start with a very simple item that will only take a little amount of time to do and then expand the scale from there.

The measurements used for estimation can for example be T-Shirt sizes (S/M/L/XL/XXL), At Openbravo we use a scale based on a part of the Fibonacci sequence:

If an item is found to be an 89, it must be examined and broken down into easier pieces. Things must also be broken down if they are found to be too large for the sprint ahead.

The pieces must however be self-contained in terms of user value.

Example:

Sorting 1000 address book cards by family name and first name – the goal is to make them easy to find for a person searching someone specific. A valid breakdown needs to consider this intended value and then deliver it in steps, e.g.:

Each of these 3 steps gives value to a person looking for a card and each can be delivered to the user after being executed.

An invalid breakdown would be:

In this sequence we could deliver customer value only after the last item, not at every iteration. Such an approach is perfectly valid inside a sprint, but the substeps cannot be an acceptable deliverable.

Things to keep in mind:

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