Which British economist was Erwin Rothbarth a research assistant for that changed the theory of economics?
Erwin Rothbarth:  He worked as a research assistant for John Maynard Keynes and made important contributions to the measurement of GDP and the modelling of individual consumption. John Maynard Keynes: John Maynard Keynes, 1st Baron Keynes {'1': ", '2': ", '3': ", '4': "} ( ; 5 June 1883 – 21 April 1946), was a British economist whose ideas fundamentally changed the theory and practice of macroeconomics and the economic policies of governments.
John Maynard Keynes