I'm looking for a formula that can incorporate economies of scale and really don't know where to begin, so I came here.

The specific situation that I am looking to use this formula for is to reflect the economies of scale in how much labor is needed as the physical square footage of a business grows. What type of formula would I use for that? Does anyone know of a good reference that I could use while developing this? Any direction that someone can point me in would be very helpful.

Thanks.