Solow's model of economic growth, often known as the Solow-Swan neo-classical growth model as the model was independently discovered by Trevor W. Swan and published in "The Economic Record" in 1956, allows the determinants of economic growth to be separated out into increases in inputs (labour and capital) and technical progress. Using his model, Solow calculated that about four-fifths of the growth in US output per worker was attributable to technical progress.