Insightful observation study: > We knew from studies in the 1950s comparing London bus drivers and London bus conductors that lived in the same environment, bu

Insightful observation study: > We knew from studies in the 1950s comparing London bus drivers and London bus conductors that lived in the same environment, but one — they had the bus drivers who were sitting, the conductors were standing, and the heart disease rate among the drivers was twice that of the conductors.