f****ing estimates
DESCRIPTION
People are bad estimators. We all know it and still customers ask "when will it be done". This talk lists a dozen explanations why estimating doesn't work and how potentially we can solve the more global problem of needing them.TRANSCRIPT
f***ing estimates
procrastination
planning fallacies
gsm paradox
who to blame
and what to do??
1.what’s the problem?
Denver Intl. Airport
Denver Intl. Airport
$2 billion more expensive16 months later
Eurofighter Typhoon
Eurofighter Typhoon
Spent: $19 billion.$7 billion.54 months later…
Sydney Opera House
Sydney Opera House
Spent: $102 million.
$7
million.
10 years later…
Vicious Cycle in IT
BUSINESS WANTS A LOT
WE GIVE UNREALISTIC ESTIMATES
WE FAIL TO DELIVER
BUSINESS STARTS TO PRESS
IT BECOMES EVEN HARDER TO
DELIVER
Will they finish in time?
Let’s run an experiment!
A simple task
+ = $1,10
The bat costs $1,00 more than the ball.How much does the ball cost?
Planning Fallacy
http://en.wikipedia.org/wiki/Planning_fallacy
Planning Fallacy
optimism bias
wishful thinking
Student were asked to
50%
75%
99%
assign probabilities of completion time
1.Nov 20.Nov 10.Dec
what would you think?
50%
75%
99%
14% 19% 45%
real completion rate
1.Nov 20.Nov 10.Dec
Estimating time in real life
Planning Fallacy
wishful thinking
procrastination
optimism bias
student’s syndrome
Planning Fallacy
wishful thinking optimism bias
student syndrome
procrastination
perfectionism
“Anything less than perfect is unacceptable”
“Work takes as much time as you have”
Parkinson’s Law
Planning Fallacy
wishful thinkingoptimism bias
student syndrome
procrastination
perfectionism
gps paradox
Krivitsky’s ZapadLaw:
To arrive sooner – you need to drive much
faster.
To be later – you don’t need to do
anything.
Planning Fallacy
wishful thinking optimism bias
student syndrome procrastination
perfectionism
gps paradox
delay propagation
E. Goldratt
Delays get accumulated.
Early completions
get lost.
Planning Fallacy
wishful thinking optimism bias
student syndrome procrastination
perfectionism
gps paradox
delay propagation
F***
Will they finish in time?
HIGH CHANCES THEY
WON’T
Will they finish in time?
Scientists joke
Holfstandter’s law:
It always takes longer than you expect, even
when you take into account
Holfstandter’s law.
Last manager’s bullet
time
4x
3x
2x
1.5x
Last manager’s bullet
time
4x
3x
2x
1.5x
Cone of Uncertainty by Barry Boehm
Last manager’s bullet
Commitment
CommitmentCommitment
Commitment
Commitment
Commitment
Commitment
Commitment
CommitmentCommitment
GUESTIMATES
2.what to do?
1. CREATE SENCE OF URGENCY
2. NEVER ESTIMATE ALONE
3. ESTIMATE IN SIZE UNITS
4. MEASURE VELOCITY
5. DERIVE TIME = SCOPE/SPEED
6. INVOLVE CUSTOMERS
7. INCREMENTALLY BUILD
ONE MORE TIME
1. Create …2. Never …3. … size …4. Measure …5. … = … /…6. …. customers7. Incrementally …
