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. Faith healers do it with whatever they can lay their hands on Farmers spread it around. Farmers do it in the dirt. Farmers do it with cows, sheep and other assorted animals.