21 Experiments to Increase Your Velocity with Queuing Theory & Theory of Constraints

21 Experiments
to increase
your Velocity
www.journey-to-better.com

Chaos in development
• Rushing
• Competing
• Shifting goals
• Misalignment
• Indecision
• Shortcuts

Terminology
Velocity ~= Throughput

Source of Experiments
Two Theories
Four Principles
21 Experiments

Queuing Theory

Serious math
Not for today

Simple principles
To increase velocity, reduce
Utilisation Batch Size Item Size

System with Variability
Why reduce utilisation?
Velocity
Cycle
Time
Resource
Utilisation

Tipping point
Utilisation0 100
CycleTime
Tipping Point
Some examples:
• Computer CPU
• Building Fire Exit
• Road

Tipping Point in action

Why reduce batch size?
Littles Law
Avg. Cycle Time =
Work In Progress (WIP)
Avg. Velocity
Velocity
Cycle
Time
WIP
Batch
Size

Why reduce item size?
Velocity
Queue
Size
(WIP)
Item
Size
Predictability
Bad
Variability
Cycle
Time

Improving freeway velocity
Image by Atlantacitizen at the English language Wikipedia, CC BY-SA 3.0,
https://commons.wikimedia.org/w/index.php?curid=1811360

Reducing utilisation
Image by: https://www.flickr.com/photos/highwaysagency/
• Radio messages
• Signs
• Promote Car Pooling
• Promote Public Transport
• Tolls
• High Taxes and fees
• Limit access by registration
• Add more lanes

Reducing batch size
Image by: https://www.flickr.com/photos/29233640@N07/
• Control entry points
• Stagger work times
• Multi nucleolus city

Reducing item size
Image by: https://www.flickr.com/photos/null0/
Replace Buses with Cars, Cars with Bikes.

Queuing Theory
is baked into
agile & Scrum
Good news!
Image by: https://www.flickr.com/photos/jeffrey

Queuing Theory in agile
agile lowers Utilization by
• Promoting sustainable development.
• Customer collaboration.
agile lowers Batch Size by
• Focus on early delivery of Working Software.
agile lowers Item Size by
• Focus on simplicity & business feedback.
Image: http://www.agilemanifesto.org/

Queuing Theory in Scrum
Scrum lowers Utilization by
• Team members 100% allocated.
• Team pulls in work to sprint.
Scrum lowers Batch Size by
• Sprint length.
Scrum lowers Item Size by
• Time boxing & D.O.D.

Utilisation experiments
• Pull in less total Story Points (-20%)
• Commit to less team hours (-20%)
• Limit # of I.P. User Stories (p/2)
• Show requesters your Scrum board

Batch size experiments
• Split up Releases (½)
• Split up Epics/Features (3 to 12)
• Shorten your Sprints (-1w)

Item Size Experiments
• Split up your User Stories (# in sprint ~= p)
• Use Spikes
• Practice Simplicity
• Split up your Tasks (max 1d)

To increase velocity:
Lower
Utilisation
Work on
smaller batches
Work on
smaller items
Queuing Theory Summary

Theory of Constraints

r0002 | flagstaffotos.com.auCanon 20D + Canon 400mm f/5.6 L - Own
L 1.2, https://commons.wikimedia.org/w/index.php?curid=5305901
Why add just one lane?

Focusing our efforts
Idea
Process
A
Process
B
Process
C
Customer
• A?
• B?
• C?
• A, B & C?
• Need more info?

Focusing our efforts
5 units
per week
2 units
per week
3 units
per week
Idea
Process
A
Process
B
Process
C
Customer
• A?
• B?
• C?
• A, B & C?
• Need more info?

Theory of Constraints (TOC)
"a chain is no stronger than its
weakest link“
Improving strong links, does not
strengthen the chain.
To achieve more of your goal,
improve your weakest link.

Five Focusing Steps
Constraint
1. Identify the constraint
2. Cheap changes
3. Align everyone
4. Expensive changes
5. Repeat

Applying TOC in Scrum
We are going to:
1. Map team workflow
2. Populate a Scrum board
3. Use TOC to increase velocity

Backlog Analysis Coding Review Testing Accept Done
Map team workflow

Populate with current state

1. Identify the constraint
Symptoms
• Work waiting in front of the constraint.
• Resource is heavily stressed.
• Starvation downstream.
Constraint

Where is the constraint?

Doing Ready
Split Testing column
1st Possibility

Doing Ready
Split Testing column
2nd Possibility

Doing ReadyDoing ReadyDoing ReadyDoing Ready
Split all other columns

2. Cheap Changes
Some experiments:
• Shield them from interruptions.
• Limit their WIP.
• Reduce their non value adding work.
No overtime!

(5)
Cheap Changes
Limit WIP in Testing

(5)
Let it run
Constraint remains

3. Align everyone
Some experiments:
• Limit WIP of upstream to match.
• Upstream do preparation work.
• Upstream improve their quality.
• Pair upstream with constraint staff.

(5)(5)(5)(5)
Align everyone
Match upstream WIP to constraint
Devs do more test prep work.
Dev-QA pairing

(5)(5)(5)(5)
Let it run
Constraint remains

4. Expensive Changes
Some experiments:
• Improve their tools.
• Improve their environment.
• Improve their team work.
• Hire more people.

(5)(5)(5)(5)
Expensive Changes
Improve tools (reduce manual effort)
Get Devs to help execute tests
Hire another tester

(5)(5)(5)(5)
Let it run
Constraint has been broken

5. Repeat
• The bottleneck should now have shifted.
• Start all over again.

Scrum enables TOC
• Task board
• Stand up
Identify
• Focus on Sprint Goal
• Scrum Master
Cheap
Changes
• Shared Team Success
• Self Organising Team
Align
Everyone
• Retrospective
• Self Organising Team
Expensive
Changes

Questions
Analogies
Utilisation, Batch Size, Item Size
Queuing theory in Agile
Queuing theory in Scrum
Improving the weakest link
Five Focusing Steps
Scrum enables TOC
Real life examples
Experiments
Contact: @andrewrusling arusling@halfbrick.com
Slides: http://bit.ly/21ExperimentsToImproveYourVelocity

QT Experiment Summary
• Pull in less total Story Points (-20%)
• Commit to less team hours (-20%)
• Limit # of I.P. User Stories (people/2)
• Show requesters your Scrum board
• Split up Releases (½)
• Split up Epics/Features (3 to 12 sub items)
• Shorten your Sprints (-1 week)
• Split up your User Stories (# in sprint ~= people)
• Use Spikes
• Practice Simplicity
• Split up your Tasks (max 1d)

TOC Experiment Summary
• Shield them from interruptions.
• Limit their WIP.
• Reduce their non value adding work.
• Limit WIP of upstream to match.
• Upstream do preparation work.
• Upstream improve their quality.
• Pair upstream with constraint staff.
• Improve their tools.
• Improve their environment.
• Improve their team work.
• Hire more people.

21 Experiments to Increase Your Velocity with Queuing Theory & Theory of Constraints

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21 Experiments to Increase Your Velocity with Queuing Theory & Theory of Constraints