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Estimation

In Agile methodologies, some principles and tools are often used for planning and time estimation.

Story points

Story points can be used instead of absolute time units, such as hours or day.

Principles

  • Abstract metric that measure work complexity, amount, risk, uncertainty and difficulty.
  • They shouldn't be used as a way to assign detailed deadlines and resources.

Guidelines

  • Define an upper limit. No individual task should be more than 16h of work, as it's too difficult to estimate large tasks with confidence.

Burndown chart

The burndown chart is a graphical representation of work left to do versus time.

Velocity

Velocity is a metric to measure the amount of work done.

Planning poker

Planning poker is a gamified estimation technique.

Preparation

  • Select a Moderator (e.g. the PO) who usually don't play
  • Define cards with numbers on it
    • Values represent time (hours, days) or more likely Story points.
    • You can even define a card with an unsure option, like a "?" sign.
  • Team members receive all the same cards

Procedure

  • The Moderator gives an overview of a task, typically a User Story.
  • Discussions occur with the team members to clarify assumptions and risks.
  • Team members vote by putting a card down.
  • Everyone reveals their card simultaneously.
  • People with high and low estimates justifiy their choice, discusssion is opened.
  • We repeat the estimation until a consensus is reached.

About cards values A non-linear suite is better since the estimation get harder when the choice is between two close numbers. Different sequences can be used:

Read more: Weber–Fechner's law of change

Resources