Agile, and in particular Scrum, is about creating a self-managed and self-organized team.
Even if in a context different than software development (self-managing teams in a telecommunications company), this paper shows that self-managing teams are more effective than comparable traditionally managed groups that perform the same type of work.
Some months ago I read an MSc in Computer Science thesis that can be very useful for your purpose: An Investigation of Team Effectiveness in Agile Software Development by Lars Martin Riiser Haraldsen. Its main objective is to investigate:
How does the Scrum methodology facilitate team effectiveness and what are the advantages and disadvantages?
The author defines team effectiveness as a:
[...] measure of a team working together in such a way that the core goals are accomplished within a certain time frame and the team members are satisfied.
The model adopted is based on this paper written by Salas, Sims, and Burke. According to these authors, the core components of teamwork include: team leadership, mutual performance monitoring, backup behavior, adaptability, and team orientation. All of these areas are needed to achieve good team effectiveness, but their implementation can be different from project to project.
I suggest you to give a look at Chapter 5 to see the author's findings in detail.
You will see, for example, that a shared mental model and a common understand of what is needed to be done in the next sprint facilitates teamwork.
It is highlighted that burn-down charts are more than a way to monitor the work progress. They show the work effort of the team together and make developers feel they contribute to the project.
Daily scrum meetings, sprint planning, review, and retrospective are all elements that can facilitate mutual performance monitoring and team orientation.
Effective backup behavior can be ensured by practicing pair programming.
From Chapter 6:
Overall, I have found that Scrum facilitates teamwork and will in most areas increase team effectiveness. [...] the studies also show that when using agile development, such as Scrum, and follow the guidelines correctly, teams are satisfied and productivity improves.
In this blog post by Scott Ambler you can find a comparison among software development paradigms (it is the result of the IT Project Success Survey, run in November and December of 2013).
Some findings include:
- Agile and Lean strategies are more effective than traditional strategies on average.
- Ad-hoc project teams (no defined process) and traditional project
teams have lower success rates than agile/iterative project teams.
- There is no common definition of software development success (in
terms of time/schedule, ROI, stakeholder value, and quality).
- Only 8% of respondents indicated that their definition of success
included all three of delivering according to schedule, within
budget, and to the specification.