That's just regular density (smart/total). The article says that's what most economists use, but it's not automatically better - and density is a bit loose of a

That's just regular density (smart/total). The article says that's what most economists use, but it's not automatically better - and density is a bit loose of a concept anyway. I'd say it comes down to whether you're interested in a bounded product (infrastructure) or an unbounded one (innovation). A good argument could be made for spreading degrees around geographically, focusing on area instead of population, but it couldn't be stated with any accuracy without a good model of the likely nonlinear effects of degree densities on both types of goals.