User stories are estimated in story points to plan project timelines. Story points are a relative unit used to estimate complexity rather than time. The team estimates stories together by first independently assigning points, then discussing to converge on a shared estimate. Velocity is calculated based on the number of points completed in an iteration to predict future capacity. Pair programming may impact velocity but not the story point estimates themselves. Estimates should consider the story complexity and effort from the team perspective rather than individuals.

1. User Stories Applied:
For Agile Software Development
–
Ch 8. Estimating User Stories
Chen Jing Fung @iii
2011/6/20
Ref: How to write, gather ideas,
http://fungsiong.blogspot.com/

2. Estimating user stories
• The reason:
– Every project (story) has it time limit!! => need
to understand how long will finish
Force to
• Basic idea about estimation consider all
other possible
– Story points (basic unit in estimation) impacts
• Each team has their nice feature of story points in
the elapsed time
For a complexity story
– A ideal day > A ideal week
No meetings, no email, no phone calls …
– Estimate as a team > a individual
• Don’t know who will join the stories
• The team involved in coming up with the estimates

3. Story points – estimation method (1)
1st round:
• Estimating (vertical) 5 3 1
– Key: every story isn’t • Share some reasons
same
– Talk with customers
customer Before After 2nd round: Moving close (converge)
Ans.
ask 4 4 3
– Triangulate the estimates
point 1 2 3 5 8 13
developers 40, 80 >
– Set story points 79, 80
point range: ½ , 1, 2, 3, 5, 8, 13, 20, 40, 80 To close
• 20 * 1 point  > 1* 20 Accuracy !!
points uncertainty Compare with the others

4. Story points – estimation method (2)
• Using Story Points
– After finished an iteration, the team can counts # of
story points (= velocity)
• based on 1st iteration <= Good!!
• Accuracy isn’t important
– Total: 300 points
– 1st iteration: done 50 points/week > predict: 30 points/week (what is
velocity? 30 or 50)
– 3 conditions to keep velocity on 1st iteration
» Nothing unusual (no accident), using a consistent manner, 1st
iteration must be independent
– The Central Limit Theorem: Σ #independent samples ~ normally
distributed
• Pair program
– No effect on story point estimates
Based on
– Relevance with velocity!! ideal day Based on
• Ex: Velocity Ideal pair
Velocity
3 , 3 = 6 p/w = 4 p/w days

5. Summary
• Use story points, keep some facts in mind
– Your team’s points ≠ my team’s
– Σ #story points ≠ Σ #individual stories points ≠ Σ
#task story points
• Estimate stories in story points
– Consider: complexity, effort or duration of a story
• Estimate points based on a team >
individuals
• Triangulate an estimate by comparing it to
other estimates
• Pair program just affect to the velocity
– Not story points Ref: How to write, gather ideas,
http://fungsiong.blogspot.com/