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“It always takes longer
than you expect,
even when you take into
Professor of cognitive
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.
The estimation game
This means that you should expect to guess
correctly for about 9 questions out of 10.
Q: How many people are in this room?
A: You ‘guess’ an interval: 2-100
1. What was the date of birth of Bram Stoker,
author of Dracula?
2. What is the population of the Republic of
3. What is the height, in meters, of the tallest
living redwood tree?
4. How many standardized (ISO 6346) steel
shipping containers exist in the world?
5. How many Boeing 747 (all models) have been
built at this date?
6. What is the total number of human deaths
attributed to H5N1 “avian” flu?
7. How many Syrian conflict refugees were
registered by UNHCR as of 1 Nov 2012?
8. What was the total wine production of France
in 2009, in hectoliters?
9. How many Olympics medals altogether have
been won to date by Austrian athletes?
10. What is the half-life, in years, of the isotope
2) 199 million
3) 115 meters
4) 20 million containers
5) 1486 747s
You can also split your content
6) 379 deaths
7) 286,000 refugees
8) 45 million hectoliters
9) 304 medals
10) 24 thousand years
How did you do?
“The primary purpose of an
estimate is not to predict a
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
not the only
Liz Keogh’s complexity model
1. Just about everyone in the world has done
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