agile estimation and planning- peter saddington

Agile Estimation and Planning

A Quick Guide to Estimating Features and Stories in Agile Development

Peter Saddington, CSM CSPExecutive EditorAgileScout.com@agilescout

White Barrel LLC. © 2011 Peter Saddington

Peter Saddington, CSP CSMIndependent Enterprise Agile CoachRally Software Agile CoachExecutive Editor AgileScout.comAuthor – Scrum Pocket [email protected]+1.404.669.6662www.agilescout.comwww.scrumpocketguide.comTwitter: @agilescout

Product Backlog• A prioritized list of

features for the given product

• Stories are implemented based on their priority

• The TOP priority Features are put into iterations first

• Changes to the iterations are OK


Prioritization Factors to Consider• Financial value of

features• Costs of

implementation• Amount of risk

removed / added• Training on new

features• PO should be

enabled


Prioritization Sliders


Sizing Features for Release


Sizing Features for Release


• Sizing and estimation happens during an Iteration Planning Meeting

• “Commitment-driven iteration planning” is setting a goal for the iteration – What we will commit to and complete!

Atlanta Snow Day


• Snow day Atlanta on 1/10/2011

• You have volunteered to help move a mountain of snow off a parking lot

• How do we estimate how long this will take?

One Way to Estimate


1. Estimate the amount of snow

2. Measure how much snow you can move

3. Estimate the total duration

Size to Velocity

Size = f(Complexity + Amount)


OR

Velocity = f(# of team members, skills, learning, distractions, sickness, absence, changes, Murphy, ?)

Velocity

• Is the rate at which a team can produce working software

• Used for estimation and planning• Measured in non-time-referent terms

(Story points)• Should not be used as a measure of

comparison across teams


Size Estimate – Derive Duration


Estimation Guidelines• In Agile, we estimate

size, not duration• Estimates are

intentionally vague (in the beginning)

• Common estimate values include:– T-shirt sizes– Scale (1-10)– Fibonacci sequence


More Estimation Guidelines

• Size (complexity) is estimated– A story is estimated to be 5 story points in relative

complexity

• Velocity is measured– The Team can deliver 15 story points in a 2 week

sprint

• Duration is derived– Based on the Team’s measured velocity of 15 story points per

sprint, it will take the Team 4 sprints to deliver 60 story pointsWhite Barrel LLC. © 2010 Peter Saddington

Approaching Estimation• Assign points for smallest and medium sized stories• Size other stories by comparison or same size


Approaches to Sizing• Estimates are made by a GROUP not an

INDIVIDUAL– Points sizes never decay– Sizes don’t change based on estimator– Use consistent relative scale

• Use techniques– Analogy– Decomposition– Planning Poker


Estimate by Comparison / Analogy

3 points

5 points

8 points

13 points


Decomposition of a Story• Goal: Break big stories into smaller stories• Goal: Define stories that can fit into single iterations• Remember: A little effort helps a lot• Remember: A lot of effort only helps a little more


Techniques – Planning Poker1. Each team has a deck of cards – Each card has a point size2. Product Owner reviews a story (1 minute per story)

A. PO should have enough knowledge about the story to discuss details

3. Analysis (3 minutes per story)A. The story is briefly discussed with questions B. The discussion should be sufficient enough to determine the complexity and relative size of

workC. Compare story to other previously sized storiesD. Each team member selects a card that is his or her estimate

4. All cards are presented to the group at the same time5. Differences and outliers are discussed (1 minute)6. Re-estimate until estimates converge

A. Time-box card considerations if time is needed to discussB. Negotiate a happy mediumC. If one individual is in disagreement, ask them if the consensus is agreeable


Breaking Stories into Tasks with Planning Poker

Using Mike Cohn’s “Ideal Time vs Elapsed Time”:How long does a football game last?

Questions to ask yourself:1.How long would [task] take: 2.If it’s all you worked on…3.You had no interruptions…4.Had everything you needed to complete it?


Ideal vs Elapsed Time in Planning Poker

It’s much easier to estimate in ideal timeIt’s too hard to estimate in elapsed time

•Start with ideal time•Define what 1 story point equals (1 story point = 1 ideal day)•Estimate how many hours each person has available•Then gradually move team’s thinknig to unit-less story points (“This story is like that story”).•“Stop talking about how long it will take” – Mike Cohn


Summary• Remember the purpose of the iteration planning

meeting is to arrive at a commitment to an iteration goal or set of product backlog items.

• Story point estimation and task estimation takes time!• The purpose of the meeting is to come up with a list of

tasks and hours.• The tasks and estimates are a tool for determining

what we can commit to!• Inspect and adapt your velocity over time with 90%

confidence intervals


Resources Used in Presentation

White Barrel LLC © 2010 Peter Saddington

1. Mike Cohn’s Presentations on “Agile Estimating and Planning” – http://www.mountaingoatsoftware.com/presentations-estimating

2. Dean Leffingwell’s book – “Scaling Software Agility”

3. Jeff Patton – http://www.agileproductdesign.com

http://www.mountaingoatsoftware.com/presentations-estimating

http://www.mountaingoatsoftware.com/presentations-estimating

http://www.agileproductdesign.com/

agile estimation and planning- peter saddington

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