project estimation: demystifying the black art. how good an estimator are you?
TRANSCRIPT
Project Estimation:Demystifying the Black Art
How good an estimator are you?
For the following questions… • Give a range (upper and lower bounds)• Do not make your ranges either too wide or too narrow• Make the range so you believe there is a 90% chance of including the right value
What is the surfacetemperature of the Sun?
What is the weight ofthe heaviest blue whale
ever recorded?
0%
5%
10%
15%
20%
25%
30%
0 1 2 3 4 5 6 7 8 9 10
Quiz Results
We stink at estimation.
Psychology works against us.
Psychology works against us.
• Feeling of ignorance• Protection of pride• Influence from expectations
Psychology works against us.
• We don’t estimate accurately• We don’t plan accordingly• We don’t execute correctly• We don’t reflect properly
Psychology works against us.
• We don’t estimate accurately• We don’t plan accordingly• We don’t execute correctly• We don’t reflect properly
Artificially Narrow Ranges
Probability of correct estimation
100%
Quiz Expectations
90%
Business Expectations
25%
Single Point Estimations
> 1%
Under-estimation
• Reduced effectiveness of project plans• Reduced chance of on-time completion• Destructive late-project dynamics
Over-estimation
• Parkinson’s Law• Student Syndrome
Give Probability Ranges
My Business Expectations
50%
25% 75%
We don’t like ranges
Put uncertainty into your estimation practices
The Golden Spiral
Planning Poker
Tainting estimates with customer expectations
We don’t know what we are estimating
“Build me a house.”
Find your project’s estimation cornerstones
How Many Bedrooms?
• 2 Bedrooms ~ 800 sq ft., 1 bathroom, 1 stall garage, small or shared yard.
• 4 Bedrooms ~ 1400 – 2200 sq ft., 2 bathrooms, 2 stall garage, yard
How Many Bedrooms?
• Prioritizing size and complexity will trigger defensive responses
• Prioritizing details will trigger optimism (i.e. size and complexity will fit inside details)
2 Day Crutch Method
2 Day Crutch Method
• Forces further exploration of unknown or large features
2 Day Crutch Method
• Forces further exploration of unknown or large features• Insists task break downs of lengthy known features
2 Day Crutch Method
• Forces further exploration of unknown or large features• Insists task break downs of lengthy known features• Teaches the wisdom of knowing when something is really unknown
Modifying estimates with “control knobs”
Psychology works against us.
• We don’t estimate accurately• We don’t plan accordingly• We don’t execute correctly• We don’t reflect properly
Estimates ≠ Plans
Estimation = Planning
“Plans are worthless — but planning is everything.” —Dwight D. Eisenhower
Psychology works against us.
• We don’t estimate accurately• We don’t plan accordingly• We don’t execute correctly• We don’t reflect properly
Not forcing clarity on project uncertainty
“It feels like 20 hours, but let’s put 24 hours to fudge it
a little bit…”
Cone of Uncertainty
$100k5
0k 2
00
k
67
k 1
50
k
80
k 1
25
k
25
k 4
00
k
Hofstadter's Law
The Gut Instinct Equation
Psychology works against us.
• We don’t estimate accurately• We don’t plan accordingly• We don’t execute correctly• We don’t reflect properly
Estimates are for visibility, not accountability
“A good estimate is a estimate that provides a clear enough view of the project reality to allow the
project leadership to make good decisions about how to control the project to hit
its targets”
[Steve McConnell, Software Estimation]
Psychology working for us.
• Be aware we don’t like being uncertain• Use estimates to humbly understand unknowns• Create team unity that is quick to extinguish unknowns
Questions?
http://gosquids.com/Estimation.pptxhttp://gosquids.com/Estimation.mp3