Why are Agile teams supposed to be small? How big are they supposed to be? Most agilists tend to agree that a team of ten people works well. But what is it about the number 10 that makes it the “magic” number? Since the start of human evolution, people formed groups to be more effective. Whether it was the hunt for a mammoth or going to war, working in teams ensured a greater chance of success. There have been various researches from Dunbar’s paper through the Scrum Guide to military formations about the ideal number of people in a team. We’ll discuss the historical, scientific and cultural reasons why 10 seems to be the magic number of forming effective teams. Does the number of team members really matter? Is 10 really the magic number. You will get an answer that will help you to create effective teams with the right amount of people. More details: https://confengine.com/agile-india-2019/proposal/7882/the-magic-number-is-10 Conference link: https://2019.agileindia.org

1. 10
The Magic Number
#10MagicNumber
Alex Sloley @alex_sloley
Gabor Devenyi @devtestrepeat
Alex Sloley and Gabor Devenyi

2. History

3. Attribution http://www.bay12forums.com/smf/index.php?topic=169526.0 (image), https://en.wikipedia.org/wiki/Paleolithic#Social_organization
Family
Band
Macrobrand

4. https://en.wikipedia.org/wiki/Decury
https://romanmilitary.net/strategy/structure/

5. Attribution TBD

6. http://sn-japan.com/sengoku/sonae.html

7. Attribution https://www.newsgram.com/874-women-will-join-military-police-indian-army-sanctions/

8. Attribution https://indianarmy.nic.in/
10
3
3
4

9. Spirituality

10. "10 commandments" (CC BY 2.0) by BhaduriAbhijit

11. Unknown author, “Sikh gurus“, public domain on Wikimedia Commons

12. "Eat money" (CC BY-NC 2.0) by eltpics

13. Numerology

14. wordart.com

15. Sports

16. There are 750 sports played around the worlds, 200+
of them are recognized by national and international federations.
While individual sports are very popular, so are team sports.
We’re examining how different sports teams are formed,
if there is a magic number or specific roles required.

17. Cricket
Two teams, eleven player in each
One team bowling, other team batting
https://www.scoopwhoop.com/15-Years-On-Heres-What-The-Cricket-Team-Of-Lagaan-Looks-Like/#.nxepjna86

18. Kabaddi
7 players in each team
Raider
https://www.prokabaddi.com/teams/1-bengaluru-bulls-teamprofile/news

20. Nature

21. Pack sizes vary, most packs have 6 or 7 members,
although some may include as many as 15 wolves.
Usually, packs are made up of between 5 and 11 wolves,
but exceptionally huge packs with 42 wolves are known to exist.
Attribution TBD

22. https://www.truthorfiction.com/photo-of-a-wolf-pack-explains-wolf-behavior/ and https://www.wattpad.com/10450812-positions-of-the-wolf-pack

23. Bengali tigers are endangered species
They lead solitary lives, hunting individually.
The home ranges occupied by adult male residents are mutually exclusive.
https://www.worldwildlife.org/species/bengal-tiger

24. Indian Elephant
Elephants live in a matriarchal family group of related females called a herd.
Herds consist of eight to 100 individuals.
Males may be associated with a herd, solitary or may live temporarily with other
males.
https://en.wikipedia.org/wiki/Indian_elephant

25. "Ant party" (CC BY-SA 2.0) by Dzipi

26. More workers working might not get more work
done, ants (and robots) show
Georgia Institute of Technology
https://tinyurl.com/antsrobots
"We noticed that if you have 150 ants in a container, only 10 or 15 of them will
actually be digging in the tunnels at any given time," said Daniel Goldman, a
professor in the School of Physics at the Georgia Institute of Technology. "We
wanted to know why, and to understand how basic laws of physics might be at
work. We found a functional, community benefit to this seeming inequality in
the work environment. Without it, digging just doesn't get done."
“More workers working might not get more work done, ants (and robots) show” by Phys.org

27. Society

28. Base 10
Decimal
Denary
0 1 2 3 4 5 6 7 8 9 10
٠ ١ ٢ ٣ ٤ ٥ ٦ ٧ ٨ ٩ ١٠

29. "old school metric system poster" (CC BY 2.0) by jasoneppink

30. "Indian Currency, Money, Rupees" (CC0 1.0) by sawaleashish920

31. Science

32. "150" (CC BY-NC-ND 2.0) by wiccked

33. “It is generally accepted that the cohesion of primate groups
is maintained through time by social grooming.”
Dunbar’s Number ≅ 150, 100-250
“In human conversations about 60% of time is spent gossiping
about relationships and personal experiences.”
For a group of 10, social grooming = 2.83%
“Coevolution of neocortical size, group size and language in humans” by R.I.M. Dunbar, Behavioral and Brain Sciences, December 1993

34. “…sociometric studies of ‘sympathy groups’ suggest
that we are only able to maintain very intense relationships
with 10-12 other individuals at any one time.”
“Whereas bird flocks can shed individuals through trickle migration
as soon as they exceed their optimal size, primate groups cannot;
they have to wait until the group is large enough to permit it to
split into two or more daughter groups of the minimum size
necessary to ensure the safety and survival of their members.”
“Human sympathy groups” by Buys, C.J. & Larsen, K.L., Psychological Report, 1979
“Coevolution of neocortical size, group size and language in humans” by R.I.M. Dunbar, Behavioral and Brain Sciences, December 1993

35. Communication Channels
n (n – 1)
2
Metcalfe’s Law
Diagram showing the network effect in a few simple phone networks. Lines represent potential calls between phones. Created by Nathan Wood in Adobe Illustrator. Woody993 at English Wikipedia.

36. How to Design Small Decision Making Groups
http://www.intuitor.com/statistics/SmallGroups.html
n
S
x=2
n!
x!(n-x)!

37. Ringelmann Effect
The Ringelmann Effect is the tendency for individual members of a group to
become increasingly less productive as the size of their group increases.
https://en.wikipedia.org/wiki/Ringelmann_effect
"Let Slip the Tugs of War" (CC BY-NC 2.0) by United States Marine Corps Official Page
https://www.teamgantt.com/blog/what-is-the-ideal-team-size-to-maximize-productivity

38. Agile

39. https://en.wikipedia.org/wiki/Extreme_programming
Scalability: Historically, XP only works on teams of 12 or fewer people. One way to
circumvent this limitation is to break up the project into smaller pieces and the team
into smaller groups. It has been claimed that XP has been used successfully on teams of
over a hundred developers.
XP
Programmer Tester Tracker Coach
Doomsayer Customer Manager

40. Scrum
Optimal Development Team size is small enough to remain nimble and large enough to complete significant
work within a Sprint. Fewer than three Development Team members decrease interaction and results in
smaller productivity gains. Smaller Development Teams may encounter skill constraints during the Sprint,
causing the Development Team to be unable to deliver a potentially releasable Increment. Having more than
nine members requires too much coordination. Large Development Teams generate too much complexity for
an empirical process to be useful. The Product Owner and Scrum Master roles are not included in this count
unless they are also executing the work of the Sprint Backlog.
https://www.scrumguides.org
https://www.scrum.org
Product
Owner - 1
Scrum
Master - 1
Development
Team 3-9

41. SAFe
Roles
Agile Team – 5-11 people
Development Team – a subset of the Agile Team, all of the generalized
specialists needed for the work
Product Owner – the owner of the Product Backlog
Scrum Master – the servant leader and coach of the team
https://www.scaledagileframework.com

42. DSDM Atern
12 roles, but in solution
development, it can easily be 10.
Well, at least it's 5+.
https://www.agilebusiness.org

43. Famous People

44. 2-Pizza Team, Jeff Bezos
"Pizza Salami" (CC BY 2.0) by pizzamasetti

45. Troy Magennis, Agile2018 San Diego, Keynote
“What’s the story about Agile Data”
https://tinyurl.com/storyagiledata
“What’s the story about Agile Data” by Troy Magennis
https://twitter.com/hw0809/status/1027244431697575936 by https://twitter.com/hw0809

46. “In every team of 100 is a team of 10 waiting to get out!”
Chet Hendrickson, Agile2015, Washington D.C.
“Extreme Programming Installed” by Amazon

47. “10 is the optimal number of people in a team such that
introverts don't have to talk to other people.”
Jim Benson, Agile2018, San Diego
“Personal Kanban” by Amazon

48. “A small group of people can get almost anything done. A large group
of people can talk about getting almost anything done.”
Jim Benson, Agile2018, San Diego
“Why Limit WIP” by Amazon

49. Conclusion
What is the perfect team size?

50. Conclusion
There is no perfect team size

51. Is there a perfect number?
No
Is there a perfect recipe?
No
Is there a perfect methodology?
No

52. Understand that people are complex
Probe, sense, and change (Cynefin)
It’s still important to have a reasonable number of people on the team!
Most of the time adding more people to the team will not lead to better
performance.
Establishing trust is key (taking away or adding people will always impact
team dynamics and trust)
Teams with no dominant voice and no free-ride tend to perform better

53. Psychological safety: Can we take risks on this team without feeling insecure or
embarrassed?
Dependability: Can we count on each other to do high quality work on time?
Structure & clarity: Are goals, roles, and execution plans on our team clear?
Meaning of work: Are we working on something that is personally important for
each of us?
Impact of work: Do we fundamentally believe that the work we’re doing matters?
Don’t forget Google’s Project Aristotle

54. Ask
What is the team goal?
What skills are needed?
What type of people are needed to address all the required skills?

55. https://tinyurl.com/AI2019MagicNumber10
"Messy Desk." (CC by-SA 2.0) by Clickflashphotos / Nicki Varkevisser

56. Thank you Bangalore,
you’ve been great, we love you all!
"Taking a Bow (or a High Kick)" (CC by-NC-ND 2.0) BY Lebatihem