Effective teams are not a magic algorithm.  Dependability. Clarity. Work Meaning. Work impact and most of all Psychological Safety:  Feeling secure to ask questions and take risks without feeling embarrassed or insecure. Google did find these traits most important.

Who is on a team matters less than how the team members interact, structure their work, and view their contributions. So much for that magical algorithm.

Google learned that there are five key dynamics that set successful teams apart from other teams at Google:

1. Psychological safety: Can we take risks on this team without feeling insecure or embarrassed?
2. Dependability: Can we count on each other to do high quality work on time?
3. Structure & clarity: Are goals, roles, and execution plans on our team clear?
4. Meaning of work: Are we working on something that is personally important for each of us?
5. Impact of work: Do we fundamentally believe that the work we’re doing matters?

The important of the security of risk taking might be surprising but it was the strongest result that Google found.  

Think about it.  If you want to ask "What's really the goal of this project?"  But you don't want to sound stupid... if you don't feel secure, you'll never ask and either (i) you'll be left out the loop and not contribute as much or (ii) the project really didn't have goal and the whole is about to waste the rest of the day in meandering nonsense...  

The questions to think about on a team level:

(Organizational behavioural scientist Amy Edmondson of Harvard first introduced the construct of “team psychological safety” and defined it as “a shared belief held by members of a team that the team is safe for interpersonal risk taking.”  Look up her work for more on this; also links to the Google work below)

1. If you make a mistake on this team, it is often held against you.
2. Members of this team are able to bring up problems and tough issues.
3. People on this team sometimes reject others for being different.
4. It is safe to take a risk on this team.
5. It is difficult to ask other members of this team for help.
6. No one on this team would deliberately act in a way that undermines my efforts.
7. Working with members of this team, my unique skills and talents are valued and utilized.

Google have a tool you can customise to address these questions and issues.  The Manager Work actions are here.  The Team effectiveness guide is here.    All work is originally Google's.   And Amy Edmondson has a Ted talk on it.  My views on it obviously not endorsed by Google etc.