Landmark developed a set of criteria for categorizing projects, including both project and team attributes. With time they have seen their "Houston Matrix" prove useful. The criteria of the Houston Matrix were
5.domain knowledge gaps, and
3.project duration, and
4.other projects’ dependencies on that project,
and scope flexibility.
The project’s overall complexity and uncertainty score is calculated on the basis of the aggregation of the individual complexity and uncertainty attribute scores.
Where i and j are the complexity and uncertainty
attributes, respectively, for a given project, and xi and yj are the individual complexity and uncertainty attribute scores from Tables 1 and 2.
Some projects are just plain "Simple" - they are like Dogs, they can be trained to be well behaved. For these, just the core Crystal Clear practices are sufficient.
But "Simple, Uncertain" projects are like Colts, with lots of unfettered energy.
The commonly seen tools of Scrum / XP help here.
Some Complex projects are corporate Cash Cows, and they're larger.
These require more rigorous requirements management and Project plans with dependencies and critical path.
While "Complex, Uncertain" projects are like Bulls, large and hard to control.
Agility is needed to steer through the uncertainty, and some rigor to manage the complexity. The best Project Managers are needed here.