Recent from talks
AD–AS model
Knowledge base stats:
Talk channels stats:
Members stats:
AD–AS model
The AD–AS or aggregate demand–aggregate supply model (also known as the aggregate supply–aggregate demand or AS–AD model) is a widely used macroeconomic model that explains short-run and long-run economic changes through the relationship of aggregate demand (AD) and aggregate supply (AS) in a diagram. It coexists in an older and static version depicting the two variables output and price level, and in a newer dynamic version showing output and inflation (i.e. the change in the price level over time, which is usually of more direct interest).
The AD–AS model was invented around 1950 and became one of the primary simplified representations of macroeconomic issues toward the end of the 1970s when inflation became an important political issue. From around 2000 the modified version of a dynamic AD–AS model, incorporating contemporary monetary policy strategies focusing on inflation targeting and using the interest rate as a primary policy instrument, was developed, gradually superseding the traditional static model version in university-level economics textbooks.
The dynamic AD–AS model can be viewed as a simplified version of the more advanced and complex dynamic stochastic general equilibrium (DSGE) models which are state-of-the-art models used by central banks and other organizations to analyze economic fluctuations. Unlike DSGE models, the dynamic AD–AS model does not provide a microeconomic foundation in the form of optimizing firms and households, but the macroeconomic relationships ultimately posited by the optimizing models are similar to those emerging from the modern-version AD–AS model. At the same time, the latter is much simpler and consequently more easily accessible for students, making it a widespread tool for teaching purposes.
According to economic historian A. K. Dutt, the AD–AS diagram first made its appearance in 1948 in a contribution by O.H. Brownlee to a textbook on applied economics. A textbook written by Kenneth E. Boulding in the same year also presented a diagram in output-price space, but unlike Brownlee's version without trying to solve the model; Boulding rather uses the diagram to warn about the dangers of aggregative thinking. Brownlee, on the contrary, went on working on the diagram and in 1950 published an article in Journal of Political Economy, which is allegedly the first published version of a full AD–AS model in Y-P space. In 1951, Jacob Marschak published lecture notes providing the first full textbook treatment of the AD–AS model, presenting the same model as Brownlee's 1948 version, though not citing neither Brownlee nor anyone else.
In the course of time, the model spread to several textbooks, becoming a standard modelling tool in principles and intermediate economics textbooks. In particular, after inflation became important in the late 1960s and 1970s, there was a need to complement the IS–LM model, which had been a dominant model for teaching purposes until that time, but assumed a constant price level, with a model that incorporated aggregate supply and consequently could provide an explanation of changes in the price level. Thus, the "IS–LM–AS model", graphically depicted as an aggregate supply curve together with a curve combining the IS and LM curves and called an aggregate demand curve, became a standard teaching model only after the inflationary supply shocks of the 1970s. In particular, two intermediate textbooks appearing in 1978 and later to be widely used, one by Rudi Dornbusch and Stanley Fischer, and one by Robert J. Gordon, together with William Hoban Branson's texbook from its second edition in 1979, all presented an AD–AS model.
From around the turn of the century, the traditional AD–AS diagram, as well as the traditional version of the IS–LM diagram, upon which the derivation of the AD curve rests, has been criticized for being obsolete. One reason is that the traditional IS–LM diagram and, consequently, AD curve rested upon the assumption of the central bank targeting money supply as its central policy variable. In contrast, central banks since around 1990 have largely abandoned controlling money supply, instead attempting to target inflation, using the policy interest rate as their main policy instrument, possibly via a Taylor rule-like strategy. Another reason is that for real-world policy purposes, it is generally not interesting to analyze the interaction between output and the price level per se, which is what the traditional AD–AS diagram illustrates, but rather between output and the change in the price level, i.e. inflation.
Because of that, the original AD–AS model has increasingly been supplanted in textbooks by a dynamic version which directly analyzes equilibria in output and inflation levels, showing these variables along the axes of the diagram. In some textbooks, the dynamic AD–AS version is referred to as the "three-equation New Keynesian model", the three equations being an IS relation, often augmented with a term that allows for expectations influencing demand, a monetary policy (interest) rule and a short-run Phillips curve. Olivier Blanchard in his widely used intermediate-level textbook uses the term IS–LM–PC model (PC standing for Phillips curve) for the same basic construction.
The dynamic AD–AS model can be viewed as a simplified version of the more advanced and complex dynamic stochastic general equilibrium (DSGE) models which are state-of-the-art models used by central banks and other organizations to analyze economic fluctuations. Unlike DSGE models, the dynamic AD–AS model does not provide a microeconomic foundation in the form of optimizing firms and households, but the macroeconomic relationships ultimately posited by the optimizing models are similar to those emerging from the modern-version AD–AS model.
Hub AI
AD–AS model AI simulator
(@AD–AS model_simulator)
AD–AS model
The AD–AS or aggregate demand–aggregate supply model (also known as the aggregate supply–aggregate demand or AS–AD model) is a widely used macroeconomic model that explains short-run and long-run economic changes through the relationship of aggregate demand (AD) and aggregate supply (AS) in a diagram. It coexists in an older and static version depicting the two variables output and price level, and in a newer dynamic version showing output and inflation (i.e. the change in the price level over time, which is usually of more direct interest).
The AD–AS model was invented around 1950 and became one of the primary simplified representations of macroeconomic issues toward the end of the 1970s when inflation became an important political issue. From around 2000 the modified version of a dynamic AD–AS model, incorporating contemporary monetary policy strategies focusing on inflation targeting and using the interest rate as a primary policy instrument, was developed, gradually superseding the traditional static model version in university-level economics textbooks.
The dynamic AD–AS model can be viewed as a simplified version of the more advanced and complex dynamic stochastic general equilibrium (DSGE) models which are state-of-the-art models used by central banks and other organizations to analyze economic fluctuations. Unlike DSGE models, the dynamic AD–AS model does not provide a microeconomic foundation in the form of optimizing firms and households, but the macroeconomic relationships ultimately posited by the optimizing models are similar to those emerging from the modern-version AD–AS model. At the same time, the latter is much simpler and consequently more easily accessible for students, making it a widespread tool for teaching purposes.
According to economic historian A. K. Dutt, the AD–AS diagram first made its appearance in 1948 in a contribution by O.H. Brownlee to a textbook on applied economics. A textbook written by Kenneth E. Boulding in the same year also presented a diagram in output-price space, but unlike Brownlee's version without trying to solve the model; Boulding rather uses the diagram to warn about the dangers of aggregative thinking. Brownlee, on the contrary, went on working on the diagram and in 1950 published an article in Journal of Political Economy, which is allegedly the first published version of a full AD–AS model in Y-P space. In 1951, Jacob Marschak published lecture notes providing the first full textbook treatment of the AD–AS model, presenting the same model as Brownlee's 1948 version, though not citing neither Brownlee nor anyone else.
In the course of time, the model spread to several textbooks, becoming a standard modelling tool in principles and intermediate economics textbooks. In particular, after inflation became important in the late 1960s and 1970s, there was a need to complement the IS–LM model, which had been a dominant model for teaching purposes until that time, but assumed a constant price level, with a model that incorporated aggregate supply and consequently could provide an explanation of changes in the price level. Thus, the "IS–LM–AS model", graphically depicted as an aggregate supply curve together with a curve combining the IS and LM curves and called an aggregate demand curve, became a standard teaching model only after the inflationary supply shocks of the 1970s. In particular, two intermediate textbooks appearing in 1978 and later to be widely used, one by Rudi Dornbusch and Stanley Fischer, and one by Robert J. Gordon, together with William Hoban Branson's texbook from its second edition in 1979, all presented an AD–AS model.
From around the turn of the century, the traditional AD–AS diagram, as well as the traditional version of the IS–LM diagram, upon which the derivation of the AD curve rests, has been criticized for being obsolete. One reason is that the traditional IS–LM diagram and, consequently, AD curve rested upon the assumption of the central bank targeting money supply as its central policy variable. In contrast, central banks since around 1990 have largely abandoned controlling money supply, instead attempting to target inflation, using the policy interest rate as their main policy instrument, possibly via a Taylor rule-like strategy. Another reason is that for real-world policy purposes, it is generally not interesting to analyze the interaction between output and the price level per se, which is what the traditional AD–AS diagram illustrates, but rather between output and the change in the price level, i.e. inflation.
Because of that, the original AD–AS model has increasingly been supplanted in textbooks by a dynamic version which directly analyzes equilibria in output and inflation levels, showing these variables along the axes of the diagram. In some textbooks, the dynamic AD–AS version is referred to as the "three-equation New Keynesian model", the three equations being an IS relation, often augmented with a term that allows for expectations influencing demand, a monetary policy (interest) rule and a short-run Phillips curve. Olivier Blanchard in his widely used intermediate-level textbook uses the term IS–LM–PC model (PC standing for Phillips curve) for the same basic construction.
The dynamic AD–AS model can be viewed as a simplified version of the more advanced and complex dynamic stochastic general equilibrium (DSGE) models which are state-of-the-art models used by central banks and other organizations to analyze economic fluctuations. Unlike DSGE models, the dynamic AD–AS model does not provide a microeconomic foundation in the form of optimizing firms and households, but the macroeconomic relationships ultimately posited by the optimizing models are similar to those emerging from the modern-version AD–AS model.
Recent media