# Lies, damn lies, estimates

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Presented at ACCU 2014 (accu.org) Are estimates an essential part of project planning and delivery or a waste of everybody's time? As is so often the case the answer is neither and both. In this session we discover that there is more than one kind of estimate and examine how they are typically used in an agile context. We look at what some of the great minds have said on the subject, from Steve McConnell to Demarco and Lister. We'll also consider the need for estimates from the viewpoint of the business people who have to decide whether a project proposal should receive budget. Picking up the 'No Estimates' discussion from Twitter, we'll see if there's a case to be made for always refusing to provide estimates or whether there are times that some sorts of estimation is valuable. I may not change your mind, but I intend to widen your perspective.TRANSCRIPT

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Lies, damn lies and estimates

Seb RoseClaysnow Limited

www.claysnow.co.uk

@sebrose

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DISRAELI

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Ill be back tomorrow to finish off

Youll be in by Christmas

That will be fixed before we

leave

All our previous customers are

completely satisfied

We dont make mistakes like other

builders

You wont notice were there

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Your companyNEEDS

that estimatesoonnowyesterday

(Of course we wont hold you to it)Tuesday, 15 April 14

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The project status is still green

Were 90% doneWe will deliver

with zero defects

On time, on budget every project

Its working in the test environment

Integration takes hardly any

time

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Prediction is very difficult,

especially about the future.

Niels Bohr, physicistTuesday, 15 April 14

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The primary purpose of an estimate is not to predict a projects outcome;

it is to determine whether a projects targets are realistic enough to allow the project to be controlled to meet them.

Steve McConnell, Software Estimation (2006)

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6. Introduction to Estimation Techniques7. Count, Compute, Judge8. Calibration and Historical Data9. Individual Expert Judgement10. Decomposition and Recomposition11. Estimation by Analogy12. Proxy-Based Estimates13. Expert Judgement in Groups14. Software Estimation Tools15. Use of Multiple Approaches16. Flow of Software Estimates on a Well-

Estimated Project17. Standardized Estimation Procedures

Part II - Fundamental Estimation Techniques

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The Cone of Uncertainty in Project Management

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Overconfidence

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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

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Example:

Q. How many people are in this room?

You guess an interval:Low: 30, High: 100

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

Question 1:

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What is the population of the Republic of Brazil?

Question 2:

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

Question 3:

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

Question 4:

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

Question 5:

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What is the total number of human deaths attributed to H5N1 avian flu?

Question 6:

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How many Syrian conflict refugees were registered by UNHCR as of 1 Nov 2012?

Question 7:

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

Question 8:

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How many Olympics medals altogether have been won to date by Austrian athletes?

Question 9:

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

Question 10:

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1) 18472) 199 million3) 115 meters4) 20 million5) 14866) 3797) 286,0008) 45 million hectolitres9) 30410) 24 thousand years

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How did you do?

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"We aren't really bad at estimating.

What we are really bad at is enumerating all the assumptions that lie behind our estimates."

-Paul Rook

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Forecasting

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Tracking

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A boundary object is a concept in sociology to describe information used in different ways by different communities. They are plastic, interpreted differently across communities but with enough immutable content to maintain integrity

--Wikipedia

Estimates are Boundary Objects

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They are weakly structured in common use, and become strongly structured in individual-site use. They may be abstract or concrete.

They have different meanings in different social worlds but their structure is common enough to more than one world to make them recognizable means of translation.

The creation and management of boundary objects is key in developing and maintaining coherence across intersecting social worlds.

-- Leigh & Griesemer

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http://leadinganswers.typepad.com/leading_answers/files/original_waterfall_paper_winston_royce.pdf

The original waterfall paper - Winston Royce, 1970

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How long is a piece of string?

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120 cm100 cm70 cm60 cm40 cm

E.D.C.A.B.

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... these studies which have for a few years now given rise to the claim that "research shows that people are better at relative than absolute estimation" do not in fact seem to square with that claim.

This doesn't entail that relative e

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