High Quality Content by WIKIPEDIA articles! The AD-AS or Aggregate Demand-Aggregate Supply model is a macroeconomic model that explains price level and output through the relationship of aggregate demand and aggregate supply. It is based on the theory of John Maynard Keynes presented in his work The General Theory of Employment, Interest, and Money. It is one of the primary simplified representations in the modern field of macroeconomics, and is used by a broad array of economists, from libertarian, Monetarist supporters of laissez-faire, such as Milton Friedman to Post-Keynesian supporters of economic interventionism, such as Joan Robinson.