Economists don't know how to do it. Electrical Engineers do it with more frequency and less resistance. Electrical engineers are shocked when they do it. Electricians check your shorts. Engineers do it with a first order approximation.
Engineers do it with precision.
Engineers charge by the hour. Executives do it in three piece suits. Executives have large staffs. FM Disc Jockeys do it in stereo, and with high fidelity. Factor analysts rotate their principal components.