@gil_zilberfeld

Planningwith #NoEstimates

@gil_zilberfeld

Hello!

I AM GIL ZILBERFELD

www.gilzilberfeld.comwww.everydayunittesting.com

@gil_zilberfeld

@gil_zilberfeld

That is the question

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The founders

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Why do we need

estimates?

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Ask the expert

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Why do we want

estimates?

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Better decisionsGo / No / Not now

AlternativesBe in control

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Why don’t we like giving estimates?

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Treated as commitments

InflatedWaste of time

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The main problem is…

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Do they help make better decisions?

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We’re not good at

estimating

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“Prediction is very difficult, especially about the future.” Niels Bohr,

Nobel Prize in Physics

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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.

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The estimation game

This means that you should expect to guess

correctly for about 9 questions out of 10.

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Q: How many people are in this room?

A: You ‘guess’ an interval: 2-100

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Ready?

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1. What was the date of birth of Bram Stoker, author of Dracula?

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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?

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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?

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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?

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So what happened?

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I’ll tell you

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This is what I want

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“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.”

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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

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Let’s estimate value!

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It’s not that simple

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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.

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Let’s estimate

complexity!

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History is your friend

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Small,same-size batches

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Let’s break it down!

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A few more things…

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Assume you are ignorant

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Write them down!

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“Ignorance is the single greatest impediment to

throughput.”

Dan Northhttps://dannorth.net/2010/08/30/introducing-deliberate-discovery/

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Let’s plan experiments!

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We don’t need no stinking estimates!

ANY QUESTIONS?

You can find me at:@gil_zilberfeld

http://www.GilZilberfeld.comhttp://www.EverydayUnitTesting.com