…and what you can do about it

Why things take longer than you

think…

— Full service digital agency

— Established 1997

— 62 minds in London & Bristol

— Award winning

Clients

Why do things take longer

than we think?

Theme 1: Estimates don’t make projects

late

Estimating is relatively easy,

controlling projects is hard

Before

— crystal clear scope commitment

— estimate for this scope

— clarity of project/company/client objectives

During

— chase down risks

— chase down unknowns

Project Controls

How good at estimating are you?

Put a range which gives you a 90%

chance of including the right answer

Typical results

— With Black Bullets

Source: Steve McConnell

Theme 2: The Cone of Uncertainty

Time

Unce

rtain

ty o

f est

imate

4 x

0.25 x

1 x

Source: Steve McConnell

Time

Unce

rtain

ty o

f est

imate

1.5 x

0.67 x

1 x

Source: Steve McConnell

You can be more lucky

You can’t be more accurate

The cone does not narrow itself

You narrow the cone by...

removing unknowns making decisions

designing

Time

Vari

abili

ty in t

he e

stim

ate

4 x

0.25 x

1 x

Initial Concept

Requirements

Wireframes

Visual Design

Development

Completion

When estimating, consider where you are in the Cone

Re-estimate at key points

Time

Vari

abili

ty in t

he e

stim

ate

4 x

0.25 x

1 x

Initial Concept

Requirements

Wireframes

Visual Design

Development

CompletionZone of Hope –

20%

Cape of Fear

Cliff of Despair

Theme 3: Estimates and Commitments

Your estimate is wrong

Estimates inform commitments

Estimates Inform Commitments

Commitment

Estimate

Commercial

Appetite

Capacity

Fame

If you commit before the Cone has narrowed, consider your

strategy

Time

Estimating techniques

Fingers and thumbs

Fingers and Thumbs

Team Captain

— Read out each country

— Count 1,2,3

— Everyone shows their

estimate

— Discuss and agree

Relative Estimates

Relativity

— Arrange animal cards in order of weight

— Set reference as Antelope = 3 (not 3kg)

— Put number cards next to each animals

Affinity Estimating

Affinity

— Lay the number cards in order

— Set reference as Convertible =3

One at a time each person either…

— Takes and place a new card

— Moves existing card, explaining why (must move a card if

you don’t agree).

Theme 4: Planning Fallacy

Wishful Thinking

— People focus on the most optimistic scenario for a task

— Only affects things we estimate ourselves

— Anecdotally people miss predictions but make deadlines

— Anonymous predictions less affected

— Youth/inexperience

— Young industry

Countering Wishful Thinking

— Be aware of it

— Do best case then worst case estimates

— Get second opinions

— Treat variations in estimates as a positive insight

And when we carry out work

— Give yourself milestone and deadlines

Theme 5: The Three Cs

CountComputeCompare

Count

— visible early on

— easy to

understand

— about 20 things

Compute

— do the sums Compare

— against previous

projects

Historical data for project profiles

Phase % of typical budget Budget this projectKick Off 1% £800Phase 1 8% £6,400Phase 2 12% £9,600Phase 3 15% £12,000Phase 4 22% £17,600Phase 5 30% £24,000Phase 6 12% £9,600Total 100% £80,000

Budget for this project £80,000

Theme 5: To over or under-estimate?

The project might never start

(with your company)

If you over-estimate

Parkinson’s Law‘work expands to fill the time available’

If you over-estimate

If you under-estimate

Increased time and effort

— Emergency status meetings

— Dealing with the client

— Re-estimating

— For additional deployments

for phases

— Briefing and managing extra

resource

also…

— Weakens your position with

client

— Delays other related

projects

— Delays other client’s

projects

Extr

a eff

ort /

cos

t / s

ched

ule

100% Over-estimatedUnder-estimated

Brook’s Law‘adding manpower to a late software project makes it

later’

Finally…

Tips for what you can do about it

1. Good estimates without project controls are worthless

2. Count, compute, compare (Judgement is last resort)

3. Create project profiles based on historical data to compare against

4. Treat ‘high’ estimates as a priceless warning of trouble ahead. Do

something about it.

5. Be aware of your position on the Cone of Uncertainty

6. Beware the large cost of under-estimating

7. Be clear on what scope goes with the estimate

8. Re-estimate at key points and track progress

9. Beware planning fallacy

10.Give yourself deadlines

Nairn Robertson | @nairnski

nairnrobertson.com

Software Estimation:

Demystifying the Black Art,

Steve McConnell