Scrum of scrums is a technique used to scale Scrum to a larger group working towards the same project goal. In Scrum we consider a team being too big when going over 10-12 individuals. This should be decided on a case by case basis. If the project is set up in multiple work streams that contain a fixed group of people and a common stand-up meeting is slowing down productivity: scrum of scrums should be considered. The team would identify the different sub groups that would act as a separate scrum teams with their own backlog, board and stand-up.
The goal of the scrum of scrums ceremony is to give sub teams the agility they need while not loosing visibility and coordination. It also helps ensuring that the sub teams are achieving their sprint goals and they are going in the right direction to achieve the overall project goal.
The scrum of scrums ceremony happens every day and can be seen as a regular stand-up:
- What was done the day before by the sub team.
- What will be done today by the sub team.
- What are blockers or other issues for the sub team.
- What are the blockers or issues that may impact other sub teams.
The outcome of the meeting will result in a list of impediments related to coordination of the whole project. Solutions could be: agreeing on interfaces between teams, discussing architecture changes, evolving responsibility boundaries, etc.
This list of impediments is usually managed in a separate backlog but does not have to.
The common guideline is to have on average one person per sub team to participate in the scrum of scrums. Ideally, the Process Lead of each sub team would represent them in this ceremony. In some instances, the representative for the day is selected at the end of each sub team daily stand-up and could change every day. In practice, having a fixed representative tends to be more efficient in the long term.
This practice is helpful in cases of longer projects and with a larger scope, requiring more people. When having more people, it is usually easier to divide the project in sub teams. Having a daily scrum of scrums improves communication, lowers the risk of integration issues and increases the project chances of success.
When choosing to implement Scrum of Scrums, you need to keep in mind that some team members will have additional meetings to coordinate and participate in. Also: all team members for each sub team need to be updated on the decisions at a later point to ensure a good flow of information.
The easiest way to measure the impact is by tracking the time to resolve issues in the scrum of scrums backlog. You can also track issues reported during the retrospective related to global coordination (is it well done? can it be improved?).
This should be facilitated like a regular stand-up.