Wesley Clair Mitchell (1874–1948) American statistician
Source: "Statistics and Government," 1919, pp. 45, 47, 48-51; as cited in: Arthur F. Burns. " New Facts on Business Cycles http://www.nber.org/chapters/c0386," in: Arthur F. Burns (ed). The Frontiers of Economic Knowledge. Princeton University Press. 1954. p. 61 - 106; p. 63