Arthur Okun observed that a 1 percent decline in unemployment is correlated with a 3 percent increase in GNP. This principle was tracked carefully by President Ford's Council of Economic Advisers during the recession of 1975.
In economics, Okun's law, named after economist Arthur Okun who proposed the relationship in 1962 (Prachowny 1993), describes a relationship between the change in the rate of unemployment and the difference between actual and potential real GDP.