@gil_zilberfeld

To Estimate or #NoEstimateGil Zilberfeld

#APIL15

@gil_zilberfeld

Who Am I

Agile helper

Software improver

Author of “Everyday Unit Testing”

www.gilzilberfeld.com

www.everydayunittesting.com

@gil_zilberfeld

@gil_zilberfeld

#NoEstimates

Woody Zuill Neil Killick Vasco Duerte

@gil_zilberfeld

Why do we need estimations?

@gil_zilberfeld

@gil_zilberfeld

Why do we want estimations?

@gil_zilberfeld

We want estimations in order to…

•Make better decisions•Go/No go•Compare alternatives

•Be in control•Dependencies

@gil_zilberfeld

So why don’t we like giving them?

@gil_zilberfeld

Estimates are sometimes…

•… treated as commitments

•… inflated by others

•… waste time and money

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But the main problem is…

@gil_zilberfeld

Do they really help in…

•Making better decisions?

•Being in control?

@gil_zilberfeld

We suck at estimating.

@gil_zilberfeld

Niels Bohr, Nobel Prize in Physics

“Prediction is very

difficult, especially

about the future.”http://en.wikipedia.org/wiki/Niels_Bohr

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The cone of uncertainty

http://www.construx.com/Thought_Leadership/Books/The_Cone_of_Uncertainty/

@gil_zilberfeld

Douglas Hofstadter, Professor of cognitive science

“It always takes longer

than you expect, even

when you take into

account Hofstadter's Law”

http://en.wikipedia.org/wiki/Douglas_Hofstadter

@gil_zilberfeld

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.

This means that you should expect to guess

correctly for about 9 questions out of 10.

Laurent Bossavit, www.bossavit.com, @morendil

@gil_zilberfeld

Example

Q. How many people are in this room?

You ‘guess’ an interval:

Low: 30, High: 100

@gil_zilberfeld

Question 1

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

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Question 2

What is the population of the Republic of Brazil?

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Question 3

What is the height, in meters, of the tallest living redwood tree?

@gil_zilberfeld

Question 4

How many standardized (ISO 6346) steel shipping containers exist in the

world?

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Question 5

How many Boeing 747 (all models) have been built at this date?

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Question 6

What is the total number of human deaths attributed to H5N1 “avian”

flu?

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Question 7

How many Syrian conflict refugeeswere registered by UNHCR as of 1

Nov 2012?

@gil_zilberfeld

Question 8

What was the total wine production of France in 2009, in hectolitres?

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Question 9

How many Olympics medals altogether have been won to date by

Austrian athletes?

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Question 10

What is the half-life, in years, of the isotope Plutonium 239?

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How did you do?

1) 1847

2) 199 million

3) 115 meters

4) 20 million containers

5) 1486 747s

6) 379 deaths

7) 286,000 refugees

8) 45 million hectolitres

9) 304 medals

10) 24 thousand years

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What do we really want?

@gil_zilberfeld

We want to..

•Make better decisions•… and feel confident about them

•Be able to manage the process•… and feel confident about the level of control

@gil_zilberfeld

“The primary purpose of an estimate is notto predict a project’s outcome;

It is to determine whether a project’s targets are realistic enough to allow the project to be controlled to meet them.”

Steve McConnell, Software Estimation (2006)

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Estimates are not the only tools

http://www.flickr.com/photos/tinou/334842339/sizes/l/

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What else?

@gil_zilberfeld

Plan with othermethods

http://blackswanfarming.com/cost-of-delay/

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Evaluate your complexity

http://lizkeogh.com/2013/07/21/estimating-complexity/

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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Collect your data

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Reduce task variance

http://www.methodsandtools.com/archive/atddreadysprintbacklog.php

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Assume you’re ignorant

http://www.amiclarke.com/unknownunknownsprint.htm

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Enumerate your assumptions

http://blog.ecoastmarketing.com/2014/01/23/assumptions-the-failure-to-ask-questions/

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Plan for deliberate discovery

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

“Ignorance is the single greatest impediment to throughput.”

Dan North

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To Estimate or #NoEstimate?

@gil_zilberfeld

Thank You!

• Questions?

• Contact me:• @gil_zilberfeld

• http://www.gilzilberfeld.com

• http://www.everydayunittesting.com