I was thinking of something more like Drake's equation.

P = T * Hbar * Cbar^Dh * E * (Po)^N

P = Productivity T = Tiredness Hbar = 2PI/(HackerNews posts read) Cbar = 2PI/(speed of light) Dh = Disruptions per hour E = Environment Po = Productivity of people you work with N = Number of people you work with