From the early days of agile, there were discussion on how to do estimations “right”. Although there’s no real mentioning them in the agile manifesto, scrum and other methodologies have put effort into this topic because there seems a need for estimations. What makes an estimation method work? And what will happen one day if we stop estimating? In this talk, I’m going to discuss where estimation works, what we do with estimations and if that’s the only way to do it. We’ll talk about how our experience and biases control them, and how the #NoEstimates discussion tries to change the way we make decisions. The next time people ask us for estimations, let’s consider the process first. Then we’ll give them an answer. Maybe.

1. @gil_zilberfeld
To Estimate or #NoEstimate
Gil Zilberfeld
#APIL15

2. @gil_zilberfeld
Who Am I
Agile helper
Software improver
Author of “Everyday Unit Testing”
www.gilzilberfeld.com
www.everydayunittesting.com
@gil_zilberfeld

3. @gil_zilberfeld
#NoEstimates
Woody Zuill Neil Killick Vasco Duerte

4. @gil_zilberfeld
Why do we need estimations?

5. @gil_zilberfeld

6. @gil_zilberfeld
Why do we want estimations?

7. @gil_zilberfeld
We want estimations in order to…
•Make better decisions
•Go/No go
•Compare alternatives
•Be in control
•Dependencies

8. @gil_zilberfeld
So why don’t we like giving
them?

9. @gil_zilberfeld
Estimates are sometimes…
•… treated as commitments
•… inflated by others
•… waste time and money

10. @gil_zilberfeld
But the main problem is…

11. @gil_zilberfeld
Do they really help in…
•Making better decisions?
•Being in control?

12. @gil_zilberfeld
We suck at estimating.

13. @gil_zilberfeld
Niels Bohr, Nobel Prize in Physics
“Prediction is very
difficult, especially
about the future.”
http://en.wikipedia.org/wiki/Niels_Bohr

14. @gil_zilberfeld
The cone of uncertainty
http://www.construx.com/Thought_Leadership/Books/The_Cone_of_Uncertainty/

15. @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

16. @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

17. @gil_zilberfeld
Example
Q. How many people are in this room?
You ‘guess’ an interval:
Low: 30, High: 100

18. @gil_zilberfeld
Question 1
What was the date of birth of Bram
Stoker, author of Dracula?

19. @gil_zilberfeld
Question 2
What is the population of the
Republic of Brazil?

20. @gil_zilberfeld
Question 3
What is the height, in meters, of the
tallest living redwood tree?

21. @gil_zilberfeld
Question 4
How many standardized (ISO 6346)
steel shipping containers exist in the
world?

22. @gil_zilberfeld
Question 5
How many Boeing 747 (all models)
have been built at this date?

23. @gil_zilberfeld
Question 6
What is the total number of human
deaths attributed to H5N1 “avian”
flu?

24. @gil_zilberfeld
Question 7
How many Syrian conflict refugees
were registered by UNHCR as of 1
Nov 2012?

25. @gil_zilberfeld
Question 8
What was the total wine production
of France in 2009, in hectolitres?

26. @gil_zilberfeld
Question 9
How many Olympics medals
altogether have been won to date by
Austrian athletes?

27. @gil_zilberfeld
Question 10
What is the half-life, in years, of the
isotope Plutonium 239?

28. @gil_zilberfeld
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

29. @gil_zilberfeld
What do we really want?

30. @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

31. @gil_zilberfeld
“The primary purpose of an estimate is not
to 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)

32. @gil_zilberfeld
Estimates are not the only tools
http://www.flickr.com/photos/tinou/334842339/sizes/l/

33. @gil_zilberfeld
What else?

34. @gil_zilberfeld
Plan with other
methods
http://blackswanfarming.com/cost-of-delay/

35. @gil_zilberfeld
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.

36. @gil_zilberfeld
Collect your data

37. @gil_zilberfeld
Reduce task
variance
http://www.methodsandtools.com/archive/atddreadysprintbacklog.php

38. @gil_zilberfeld
Assume you’re
ignorant
http://www.amiclarke.com/unknownunknownsprint.htm

39. @gil_zilberfeld
Enumerate your
assumptions
http://blog.ecoastmarketing.com/2014/01/23/assumptions-the-failure-to-ask-questions/

40. @gil_zilberfeld
Plan for deliberate
discovery
http://dannorth.net/2010/08/30/introducing-deliberate-discovery/
“Ignorance is the single greatest
impediment to throughput.”
Dan North

41. @gil_zilberfeld
To Estimate or #NoEstimate?

42. @gil_zilberfeld
Thank You!
• Questions?
• Contact me:
• @gil_zilberfeld
• http://www.gilzilberfeld.com
• http://www.everydayunittesting.com