What’s Wrong With Estimates?

A Journey with LEGO and Maths

A Well Known

Brand of

Plastic Blocks

In My World (Agile-EA)

In My Head (Helpful?)

…And It Works!

Example: Custom Load Balancing Algorithm in 2000

Focused on computational cost of calculating Averages <- SERIOUSLY!!

…And It Works! (Contd)

Healthy Respect for New Stuff!

Estimates

• Traditionally Blamed for Project Failure• We Don’t Like Being Held to Them• Blame Ensues – “You told me it would take this long” (external)– “I failed to hit my own deadline” (internal)

However, Estimates…

• Never Killed A Project!– Variance Between Estimate & Actual Time/Cost Killed it!

• Set Expectations– Uncertainty & Stakeholder Expectation Badly Managed

• Deliver one ‘half’ of Value Equation– Like it or not, cost is the other

• Salaries, Recruitment, Capex, Opex, SaaS…

• Stakeholders Don’t Understand Variance• Larger Estimates = Uncertainty Higher• Humans Better At Smaller Estimates!

ACTIVITY: Audience Participation

• Score-sheet Coming Round1. Shown Patterns of Red

Dots for 2 seconds2. Count/Estimate

Number of Dots3. 5 Second Countdown4. This will be repeated

10 times5. Swap Scorecards &

Total Results Yes, there is 3!

Question 1

5

3

12

4

Question 2

5

3

12

4

Question 3

5

3

12

4

Question 4

5

3

12

4

Question 5

5

3

12

4

Question 6

5

3

12

4

Question 7

5

3

12

4

Question 8

5

3

12

4

Question 9

5

3

12

4

Question 10

5

3

12

4

End of Activity(You can now relax)

Relevant Concepts…

• Humans Naturally Remember (& Process) 5 to 9 items– More Leads to Confusion & Complexity– Less and You’re Easily Confused :o)– Stories of 8+ Points Need Breaking Down

• Regularity Makes Estimates Easier– Low/Zero Variance– Use Lessons Learned/Code Libraries As-is– e.g. Squares Easiest to Estimate (measure one side and

square it)

However…• Coder’s World is [Mostly]

Uncertain!!• Regularity Doesn’t Exist!

– No two projects/Components are exactly the same.

• Usually > 9 items of ANYTHING– Components– Classes– Methods– Lines of Code

• Continually look at points distribution! Or do ‘1-point’ stories (e.g. #NoEstimates)

Time

Freq

uenc

y

Actual Client Data

Tackling Uncertainty• Split into Predictable Chunks, Then Aggregate• Use Small Chunks - Lowers Variability (& Confusion)• Beware Relationships! Any Relationship is Complex! Especially if Shared!• Use what you know as a baseline and LEARN!

• = More ‘Accurate’ Delivery!

= 14,4

4

3

3= + = 10

9 1

Cone of UncertaintyLarge Chunk Project (BDUF/RUP) = Long

Feedback Cycle. Slow journey to certainty

Small Chunk Project (Sprint/Iteration) = Frequent

Learning, Moves towards Certainty, Descends Cone

Faster

Predictability

Time

Uncertainty Curve

KEY

So, Get Feedback Fast!

• Make Small Changes• Change one thing!• Deploy & Evaluate Efficacy

Bigger Tasks Lose Accuracy, Reduce Certainty and ‘Quality’ of Knowledge!

Which Looks More Accurate?

Hamley’s Queen Ethar’s Lego Queen

OR

TAKEAWAY: KEEP STUFF SMALL!

Small tasks, small batches, small cycles, small timescales, small change, small planning…

BUT…

ACTIVITY: Can it be Too Small?

Team A: 2 Dev + Product Owner

• 8 sticks x 5 blocks each• Each block is a task• Each task

– Pull in stack– Take 2 blocks from stack– Place into ready

• Pay Per Delivery

Team B: 4 Dev + Product Owner

• 8 sticks x 5 blocks each• Each block is a task• Each task

– Pull in stack– Take 1 block from stack– Place in ready

• Pay Per Delivery

Question: Who Wins? Why?

Beware Context Switching

• What are context switches?– Task Done that Doesn’t

Add Value!

• The ‘Zero’ cost switch…– …Doesn’t exist!

• Switching yourself between tasks…

• But what else?

Tasks Between Stages!!– Columns, People,

Boards…

Total ReplatformsLarge Business PivotsMass Change ProgrammesEntire Codebase Rewrite…

TAKEAWAY: KEEP STUFF SMALL!

Small tasks, small batches, small cycles, small timescales, small change, small planning…

(INCLUDING CONTEXT SWITCH COST)

Thanks for Watching

LinksKanban Simulator

http://www.kanbansim.org/ Queuing Theory

http://en.wikipedia.org/wiki/Queueing_theory

Attribution All images courtesy of Google images and are the property of their respective owners

Ethar Alali @EtharUK @Dynacognetics

Managing Director & Chief ArchitectPolymath-MathMo. Programming since 9 years old. TOGAF 9 Certified, change agent. Blog: GoadingtheITGeek.blogspot.co.uk

Managing Director/CEO of Dynacognetics.Specialist Agile-EA, ICT Strategist & Advisor. Member of HiveMind Network.

Accredited Growth Voucher Advisor certified to deliver IT & Web Growth Consultancy to SMEs and Startups as part of the government’s Growth Voucher Scheme.

About Me

Accreditations & Associations

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