Team size dynamics – where is the science on this?

By Georg Fasching | blogpost

Feb 08

The magical maximum team size was heralded at 7±2. Some now say it is 5±2. The military has it as 4.

Regardless of the actual figure what is the science behind it?

Many managers and leaders fall into the common productivity trap that more people mean more progress. But bigger doesn’t mean better when it comes to the organisation of teams at work, in fact it’s quite the contrary.

Individuals who form a part of a smaller team have been scientifically proven to be more personally productive than those on larger teams. While each additional person increases the total productivity of the team as a whole, research has shown that they do so at a decreasing rate; the 5th member to join a team for example, makes a bigger impact on its productivity than the fifteenth. Let’s look at some theories as to why this happens.

Personal responsibility – Social Loafing

In one of his experiments, French professor of agricultural engineering, Maximilien Ringelmann, asked volunteers to perform the very simple task of pulling on a rope. Ringelmann (1913) found that when only one person was pulling on the rope they would give 100% of their effort, however, as more people contributed, their individual effort decreased. A similar study by Bibb Latané where participants wearing blindfolds and noise-masking headphones were asked to shout as loud as they could, produced like results; participants made less noise in groups compared to when they shouted alone. In psychology, this phenomenon of individuals exerting less effort to achieve a goal when they work in a group than when they work alone is referred to as “Social Loafing”. (Why Less is More in Teams, Mark de Rond, Aug 06 2012. The Harvard Business Review.)

“When groups get larger, you experience less social pressure and feel less responsibility because your performance becomes difficult, or even impossible, to correctly assess amidst a crowd. It’s no wonder that when credit and blame get harder to assign, you start to feel disconnected from your job.” Latané (c. 1979)

Quality of Communication

There is a cost to individual and team productivity as impairments to communication and coordination among team members snowball in larger team settings.

Founder and CEO of Amazon, Jeff Bezos famously once stood up to the suggestion that employees should communicate more with his retort “No, communication is terrible!” His equally famous two-pizza team philosophy, advocates that teams should be no larger than two pizzas can feed; communication being better between small groups. This was covered with some additional considerations in an article by Janet Choi at Bufferapp titled “The Science Behind Why Small Teams Work More Productively: Jeff Bezo’s 2 Pizza Rule“.

As Richard Hackman, Professor of Social and Organizational Psychology at Harvard University quite rightly pointed out – it is the number and management of links between members that gets larger teams into trouble. As a team grows, so does the number of links that need to be managed among members – at an accelerating, almost exponential rate. The cost of coordination proliferates with every additional member.

  • Take a two-pizza team size of, let’s say, 6. That’s 15 links between all members.
  • Double that to a team of 12. The number of links immediately shoots up to 66.
  • Finally, a small business of 50 people would have an impossible 1225 links to manage.

“Every steep jump in links also produces a steep jump in the potential for mismanagement, misinterpretation, and miscommunication.”

What’s more, there are only so many social relationships that one person can maintain. In his 2006 paper for Cognitive Edge David Snowden summarises his understanding of three numbers that relate to the natural limit on this number: 5 as the effect limit of the short term memory, 15 as a natural limit on deep trust and 150 (the Dunbar number) as a natural limit on acquaintances, normally interpreted as a limited number of individuals in respect of whom one can maintain some degree of knowledge. Just look at what happens as your list of Facebook friends grows!

Relational Loss in Larger Teams

Relational losses specifically involve perceptions about the extent to which teammates are likely to provide help, assistance and support in the face of struggle or difficulty. Psychologist and University of San Diego Professor of Management, Jennifer Mueller uncovered “relational loss” as a further element of why individuals’ efficiency decreases in larger teams.  Mueller’s theory was that a deterioration in connections between team members increased with team size, resulting in weaker performance on average by individual participants.

As she studied over 200 knowledge workers, in team sizes ranging from three to nineteen, she found those in larger teams appeared to be vastly more stressed and as a result performed worse.

“[I]n these larger teams, people were lost. They didn’t know who to call for help because they didn’t know the other members well enough. Even if they did reach out, they didn’t feel the other members were as committed to helping or had the time to help. And they couldn’t tell their team leader because [it would look like] they had failed.”

How should we define the optimal team size?

There is no definite answer or formula (that I know of) to what number constitutes the optimal team size. While The U.S. Navy Seals apparently quote 4 as “the optimal size for a combat team”, another study, related to Parkinson’s Law, suggests that any team size below 20 can work, all except for a team of 8 (where people apparently find themselves in deadlock over decision making).

On the whole however, and regardless of an actual figure, science has shown us that for more effectual  teamwork – we should be thinking smaller!

How you can put what we’ve learned into practice…

  1. Stick to single digits!
  2. Make your team feel smaller – cut out huge meetings and deploy focussed sub-groups
  3. Relational loss is a perception – find effective ways to bring your teammates together
  4. Make teamwork easier with transparency – use systems, processes and suitable tools to distribute information and power so that all feel aligned
  5. Appoint team troubleshooters – a point of contact for all team members when they feel ‘stuck’

Mapping this to Agile teams

  1. Agile teams are recommended to be 7±2 – single digits. Done; if yours is bigger, this article hopefully explained why you might want to reconsider your team size.
  2. Agile ceremonies are all-team, while working through smaller challenges are sub-groups with playback to the rest of the team as appropriate to share the learning and get feedback. Teams go through a lot of improvements on making these sessions valuable, effective, and efficient.
  3. Daily planning, regular reviews, and especially regular retrospective help the team become stronger and closer. Teams go through a lot of improvement on this, facilitated by their Scrum Master/Team Facilitator/Team Coach.
  4. Transparency is everywhere inside Agile teams, from open Product Backlogs, over visible Sprint/Work/Task Boards, all helping a sense of shared ownership.
  5. In Agile teams this troubleshooter is commonly the Scrum Master/Team Facilitator/Team Coach. Their objective is to coach the team to solve their own internal challenges and step in to address those impediments that are beyond the control and influence of the team.

It looks clear that Agile approaches and frameworks catered for the key points. Implementations however vary. Even in the best of teams there is always room for further improvement. That is a core principle of both Agile and Lean. Firstly it is the Scrum Master/Team Facilitator/Team Coach’s privilege to drive this improvement. If they’d like some acceleration, an Agile Coach who supports the organisational unit can work with them and the team that they support.

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