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Published byJoleen Stewart Modified over 9 years ago
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Project Estimation: Demystifying the Black Art
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How good an estimator are you?
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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
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What is the surface temperature of the Sun?
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What is the weight of the heaviest blue whale ever recorded?
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Quiz Results
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We stink at estimation.
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Psychology works against us.
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Feeling of ignorance Protection of pride Influence from expectations
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Psychology works against us. We don’t estimate accurately We don’t plan accordingly We don’t execute correctly We don’t reflect properly
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Psychology works against us. We don’t estimate accurately We don’t plan accordingly We don’t execute correctly We don’t reflect properly
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Artificially Narrow Ranges
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Probability of correct estimation 100%
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Quiz Expectations 90%
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Business Expectations 25%
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Single Point Estimations > 1%
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Under-estimation Reduced effectiveness of project plans Reduced chance of on-time completion Destructive late-project dynamics
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Over-estimation Parkinson’s Law Student Syndrome
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Give Probability Ranges
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My Business Expectations 50% 25%75%
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We don’t like ranges
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Put uncertainty into your estimation practices
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The Golden Spiral
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Planning Poker
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Tainting estimates with customer expectations
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We don’t know what we are estimating
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“Build me a house.”
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Find your project’s estimation cornerstones
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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
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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)
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2 Day Crutch Method
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Forces further exploration of unknown or large features
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2 Day Crutch Method Forces further exploration of unknown or large features Insists task break downs of lengthy known features
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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
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Modifying estimates with “control knobs”
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Psychology works against us. We don’t estimate accurately We don’t plan accordingly We don’t execute correctly We don’t reflect properly
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Estimates ≠ Plans
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Estimation = Planning “Plans are worthless — but planning is everything.” —Dwight D. Eisenhower
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Psychology works against us. We don’t estimate accurately We don’t plan accordingly We don’t execute correctly We don’t reflect properly
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Not forcing clarity on project uncertainty
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“It feels like 20 hours, but let’s put 24 hours to fudge it a little bit…”
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Cone of Uncertainty
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$100k 50k 200k 67k 150k80k 125k 25k 400k
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Hofstadter's Law
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The Gut Instinct Equation
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Psychology works against us. We don’t estimate accurately We don’t plan accordingly We don’t execute correctly We don’t reflect properly
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Estimates are for visibility, not accountability
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“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]
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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
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Questions?
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http://gosquids.com/Estimation.pptx http://gosquids.com/Estimation.mp3
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