Date post: | 15-Apr-2017 |
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Software |
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@gil_zilberfeld
Planningwith #NoEstimates
@gil_zilberfeld
Hello!
I AM GIL ZILBERFELD
www.gilzilberfeld.comwww.everydayunittesting.com
@gil_zilberfeld
@gil_zilberfeld
That is the question
@gil_zilberfeld
The founders
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Why do we need
estimates?
@gil_zilberfeld
Ask the expert
@gil_zilberfeld
Why do we want
estimates?
@gil_zilberfeld
Better decisionsGo / No / Not now
AlternativesBe in control
@gil_zilberfeld
Why don’t we like giving estimates?
@gil_zilberfeld
Treated as commitments
InflatedWaste of time
@gil_zilberfeld
The main problem is…
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Do they help make better decisions?
@gil_zilberfeld
We’re not good at
estimating
@gil_zilberfeld
“Prediction is very difficult, especially about the future.” Niels Bohr,
Nobel Prize in Physics
@gil_zilberfeld
The cone of uncertainty
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“It always takes longer than you expect,
even when you take into account
Hofstadter's Law”Douglas Hofstadter
Professor of cognitive science
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The estimation game
For each of the next 10 quantitative questions,
give a lower and an upper bound, such that you believe with about 90%
certainty that the correct answer lies within the interval
given.
@gil_zilberfeld
The estimation game
This means that you should expect to guess
correctly for about 9 questions out of 10.
@gil_zilberfeld
Q: How many people are in this room?
A: You ‘guess’ an interval: 2-100
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Ready?
@gil_zilberfeld
1. What was the date of birth of Bram Stoker, author of Dracula?
@gil_zilberfeld
2. What is the population of the Republic of Brazil?
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3. What is the height, in meters, of the tallest living redwood tree?
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4. How many standardized (ISO 6346) steel shipping containers exist in the world?
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5. How many Boeing 747 (all models) have been built at this date?
@gil_zilberfeld
6. What is the total number of human deaths attributed to H5N1 “avian” flu?
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7. How many Syrian conflict refugees were registered by UNHCR as of 1 Nov 2012?
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8. What was the total wine production of France in 2009, in hectoliters?
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9. How many Olympics medals altogether have been won to date by Austrian athletes?
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10. What is the half-life, in years, of the isotope Plutonium 239?
@gil_zilberfeld
1) 18472) 199 million3) 115 meters4) 20 million containers5) 1486 747s
You can also split your content
6) 379 deaths7) 286,000 refugees8) 45 million hectoliters9) 304 medals10) 24 thousand years
How did you do?
@gil_zilberfeld
So what happened?
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I’ll tell you
@gil_zilberfeld
This is what I want
@gil_zilberfeld
“The primary purpose of an estimate is not to predict a project’s outcome.
Steve McConnell, Software Estimation (2006)
It is to determine whether a project’s targets are realistic enough to allow the project to be controlled to meet them.”
@gil_zilberfeld
Let’s assume and estimate
costs!
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Estimates are not the only
tools
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Trains!
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What else?
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Value estimation
@gil_zilberfeld
Let’s estimate value!
@gil_zilberfeld
It’s not that simple
@gil_zilberfeld
Liz Keogh’s complexity model
1. Just about everyone in the world has done this.
2. Lots of people have done this, including someone on our team.
3. Someone in our company has done this, or we have access to expertise.
4. Someone in the world did this, but not in our organization (and probably at a competitor).
5. Nobody in the world has ever done this before.
@gil_zilberfeld
Let’s estimate
complexity!
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History is your friend
@gil_zilberfeld
Small,same-size batches
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Let’s break it down!
@gil_zilberfeld
A few more things…
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Assume you are ignorant
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Write them down!
@gil_zilberfeld
“Ignorance is the single greatest impediment to
throughput.”
Dan Northhttps://dannorth.net/2010/08/30/introducing-deliberate-discovery/
@gil_zilberfeld
Let’s plan experiments!
@gil_zilberfeld
We don’t need no stinking estimates!
ANY QUESTIONS?
You can find me at:@gil_zilberfeld
http://www.GilZilberfeld.comhttp://www.EverydayUnitTesting.com