The document discusses software estimation, emphasizing the challenges associated with making accurate estimates due to the complexity and uniqueness of software projects. It introduces concepts such as story points and estimation techniques like poker planning and affinity sizing, recommending relative measures over absolute ones. The document also explores the concept of sprint velocity as a measure of team progress and its calculation based on historical data.

1. Software Estimation
André Pitombeira

2. Agenda
● Overview
● Estimation
● Challenges with Estimation
● Story points
● Estimation techniques
● Sprint velocity
● Challenges with Sprint velocity
● Brainstorm
● Final considerations

3. Overview
—John Maynard Keynes. It is better to be roughly right
than precisely wrong.

4. Overview
● The problem with estimation is people
● We’re bad at making absolute estimates
○ Ideal time (hours, days, weeks)
● We’re good at making relative estimates
○ Size and complexity
● Exercise: Packing for a weekend trip

5. Estimation
● Relative measure of size
● How long a story will take (effort)
● Influenced by complexity, uncertainty, risk, volume of work
● Relative values are what is important
○ Login screen is 2
○ Checkout screen is 8
● Basic math properties should hold

6. Challenges with Estimation
● Ambiguous/changing requirements
● Estimating takes too long and still don’t get it right
● Estimations are provided by the wrong people
● Software projects are unique and ambiguous.
○ Hard to provide exact estimates
○ Exponential complexity
● Estimations are not commitments

7. Story Points
● Abstract unit of time
○ Depending on the person it can be hours, days, weeks
● The goal is to take us away from thinking in terms of absolute estimates
● Start doing estimations relatively

8. Story Points
● Fibonacci sequence
○ 1, 2, 3, 5, 8, 13, 21
● Why does it work?
○ Weber’s Law states that the difference we can identify between objects is given by a percentage
○ Each Fibonacci number is about 60% larger than the preceding value
○ According to Weber’s Law, if we can distinguish a 60% difference in effort between two estimates, we can
distinguish that same percentage difference between other estimates

9. Estimation techniques
● Poker planning
○ Each team member gives an estimation using a card
○ Create consensus
● Affinity sizing
○ Draw a vertical line on a board
○ Review stories and add them to the board
○ Determine points in the end
● Complexity buckets
○ Agree on the bucket criteria
○ Review stories and add them to the buckets
○ Combine points from the buckets and define the final story point value

10. Sprint Velocity
● Velocity it is a measure of team rate of progress used to estimate future commitments
● How to calculate a team velocity?
○ Look at the historical data from the previous sprints
○ Calculate a confidence interval (usually ~ 90%)
● How to use them?
○ Size -> Calculation -> Duration
■ 300 points is the size
■ 20 points is the velocity
■ The duration is 300/20 = 15
○ It helps the team to do a rough estimation of when something is gonna be released
● Practice: Velocity chart on Jira

11. Challenges with Sprint Velocity
● Number of team members
● Unresolved impediments
● Unclear acceptance criterias
● Shifting priorities
● Interruptions
● Multi-tasking
● Skill level
● New members
● Team dynamics
● Vacation/sick leave

12. Brainstorm
Hands on

13. Questions?

14. Thank you!