The Pyramid's Volume Is Constant
We can now posit that the volume contained in the pyramid is a constant for a given team. That is, reality dictates that only so much "stuff" will fit into the project pyramid, based on that team's capabilities. This makes sense, because the pyramid's volume is proportional to
As one goes up, the other must go down. This is another way of saying that there is a "conservation law" at work here: The product of the base areawhich represents the project difficulty due to the specification of the four parameterstimes the altitude (representing the probability of success) is proportional to a "conserved" volume.
What determines the pyramid's volume? Two things. First, the capabilities of the project team, as I have already mentioned. And second, the degree to which the project team members are grappling with unfamiliar problems. A highly capable team implies a larger volume:
and lots of new problems and unknowns implies a smaller volume:
So, given a constant volume corresponding to the project team and initial set of unknowns, what do you have to do if you want to make the altitude higherthat is, if you want to increase the probability of success? By the logic of elementary solid geometry, you must make the base smaller. You do this by reducing the lengths of one or more sides of the base, thereby making the project easier.
Remember: Volume is proportional to base times altitude, regardless of the base's shape.