Post on 15-Jun-2020
@gil_zilberfeld@gil_zilberfeld
Better Estimation and Planning
@gil_zilberfeld
Hello!
I AM GIL ZILBERFELD
www.gilzilberfeld.com
www.everydayunittesting.com
@gil_zilberfeld
@gil_zilberfeld@gil_zilberfeld
Material available on
https://github.com/gilzilberfeld/better-estimation
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“Prediction is very
difficult, especially
about the future.” Niels Bohr,
Nobel Prize in Physics
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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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Why estimate?
@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.
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The estimation game
This means that you should expect to guess
correctly for about 9 questions out of 10.
The estimation game
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Q: How many people are in this room?
A: You ‘guess’ an interval: 12-67
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Ready?
Have a pen and paper to write your ranges down!
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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) 1847
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?
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So what happened?
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How do estimates help the product?
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Estimates are waste!
Maybe a necessary waste
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Are they working for you?
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Would you call a 15 min planning session a win?
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Story points
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Story points are thinly obfuscated time, no more and no less.
Ron Jeffries
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Why obfuscate time?
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I am not sure I invented story points, but if I did, I’m sorry now.
Ron Jeffries
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Story points
◉ Everybody knows the “algorithm”
◉ The business talks in dates
◉ We want to encourage ubiquitous language and
openness
◉ Just use time measurements
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Planning Poker
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https://www.amazon.com/Agile-Stationery-Estimation-Poker-players/dp/B01MDTJDST
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Planning Poker
◉ Fibonacci numbers
◉ Full story estimation
◉ Promote discussion through variation
◉ All the team and just the team
◉ No HIPPOs
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Not so helpful questions
◉ Is it a 3 or a 5?
◉ Should we take the top or the average?
◉ Should we go another round?
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Planning Poker
◉ Process that requires practice
◉ Make it quick or find another way
◉ Discuss the “why” behind variation
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Consensus is not that important
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Let’s do some estimation
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The cheese marketplace
◉ Buy and sell cheese in our marketplace
◉ Buyers can buy different types of cheese from
different countries with different currencies and get
a single bill
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The cheese exchange
◉ Each line item comes with cheese type, amount,
price per kilo, and exchange rate against the EUR
◉ Bill Example:
Gouda::10::3.12::GBPPecorino::14::4.25::USDCheddar::8.99::CHF
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The cheese exchange
◉ Allow adding, modifying and deleting exchange
rates
◉ Process multi-currency bills and calculate the
total in required currency
◉ API based application accessible through mobile
and web and integration with at least 5 suppliers
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Group Exercise (10 mins)
◉ Examine the test plan
◉ Pick the 10 important items (we’re going to cover
them first)
◉ Define the estimation scale
◉ Keep the personal and group estimation for later
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Group exercise
◉ Do some planning poker
◉ Write down the variances and why
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What is a good estimate?
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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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How confident are you with your estimates?
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Liz Keogh’s Complexity Scale
1. We all know how to do it
2. Someone on our team has done this before
3. Someone in our company has done this before
4. Someone has done this outside our organization
5. Nobody has done this before.
https://lizkeogh.com/2013/07/21/estimating-complexity/
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Group exercise
◉ Rate the different items
◉ How confident are you now?
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Experience based estimation
◉ Our estimates are based on our experience
◉ “I’ve done this before” -> It will probably be faster
than my last time
◉ “You’ve done this before” -> It will probably be
faster with your help
◉ “We haven’t done this before” -> It will take time
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Comparative estimations
◉ We’re optimistic and want to please
◉ We don’t remember what it took last time
◉ We don’t remember how it looked last time
◉ We don’t foresee what will happen
◉ Our estimates suck
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Group exercise: Let’s make history!
◉ Roll the dice for each test case 5 times
(iterations)
◉ For each complexity level :
1 - roll once2,3 – roll twice
4,5 – roll 4 times
• Estimate the next iterations based on history
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What is velocity?
And how do you calculate it?
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Velocity is a measure of the amount of work a team can tackle during a single sprint
https://www.scruminc.com/velocity/
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What happens if velocity is a goal?
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But stories are not the same size!
◉ Make them the same size!
◉ If all stories / tasks are the same it’s easy to
count
◉ Count same-size stories over time, that is your
velocity
◉ Then estimation goes away!
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Projection over estimation
◉ Projection is what we think our progress would
be, based on the recorded past.
◉ We can be more statistically “precise”
◉ But it only works if people understand statistics
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Monte-Carlo simulation
◉ Based on small sample size, create projections in
different confidence levels
◉ The sample need relevance into the projected
future
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Demo: Monte Carlo Simulation
◉ Troy Magennis tools
◉ You need relevant data
◉ You need people who understand probabilities
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Group Exercise - How long will it take?
◉ Use
➢ The rolls as history
➢ Split rate based on complexity
➢ Maximum throughput is # of people on team
- 2
◉ When are all the tasks be done?
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So what is this #NoEstimates nonsense?
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Estimates are not the only
tools
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Trains!
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Value estimation
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Write them down!
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Summary
◉ Estimates are not going away
◉ History is the greatest projector
◉ Use with other tools to make decisions
◉ And if you’re lucky, #NoEstimates await
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Thanks!
ANY QUESTIONS?
You can find me at:
@gil_zilberfeld
http://www.GilZilberfeld.com
http://www.EverydayUnitTesting.com