# Group Size

### From Collaboratory

What is the "optimal" group size? The "right" number depends on purpose, but it also depends, to some extent, on human capabilities.

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## Group Size

Christopher Allen wrote a series of posts on group size. The sizes he proposes center around the Rule of Seven and the Dunbar Number. For example, he suggests that working groups should be between 7-13 people. (He refers to this upper limit as the "Judas Number.")

The number three has some importance in network theory.

## Breakouts or Whole Group?

One process question that always comes up is whether or not to break out into smaller groups or whether to keep a whole group together for discussion. Many things factor into this decision. First, it's important to note that every breakout should be followed by a whole group report-out, so synthesis / cross-fertilization happens. Second, it's also important to realize that -- despite our greatest hopes -- it's not possible to include large groups on every aspect of a conversation.

When considering whether to breakout into groups, and if so, the size of each group, you can use a simple equation as a guide:

**Time / Group Size = Individual Time to Talk**

In other words, if you have an hour and a group of 15 people, each person will have 4 minutes to talk if everyone takes an equal amount of time (which almost certainly won't happen. If you take that same group and break them out into three groups of 5 for 30 minutes, then each person will have at least 6 minutes to talk, and you still have 30 minutes for whole-group synthesis.