5.3Communication planning

As a project's headcount grows, the number of possible communication channels among participants increases more sharply than intuition suggests. Adding members without understanding this structure can let communication complexity overwhelm project management and actually reduce productivity. This section covers calculating the number of channels and how to handle its growth, along with choosing a communication method and medium appropriate to the situation.

5.3.1Communication channels n(n-1)/2 and the rapid growth from adding members

• If a project has n participants, the potential number of communication channels among all possible one-to-one pairs is given by n(n-1)/2. This equals "the number of ways to choose a pair of 2 people from n." Even as headcount grows linearly, the channel count balloons at a rate close to the square of headcount, so the PM must always weigh the benefit of adding members against the cost of managing the resulting communication.
• Manual check: going from n=5 (10 channels) to n=8 (28 channels) is a 1.6x increase in headcount but a 2.8x increase in channels. n=5 gives 5×4/2=10; n=8 gives 8×7/2=28. Rather than avoiding additional headcount outright because of this nonlinear growth, an effective practical design judgment is to avoid a structure where everyone communicates directly across every channel, and instead introduce roles for aggregating and distributing information (e.g., a hub structure via team leads, a regular reporting line) to narrow the channels actually used.