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Macroeconomics (from the Greek prefix makro- meaning “large” + economics) is a branch of economics dealing with performance, structure, behavior, and decision-making of an economy as a whole. For example, using interest rates, taxes, and government spending to regulate an economy’s growth and stability. This includes regional, national, and global economies. According to a 2018 assessment by economists Emi Nakamura and Jón Steinsson, economic “evidence regarding the consequences of different macroeconomic policies is still highly imperfect and open to serious criticism.”# ISO certification in India

Macroeconomists study topics such as GDP (Gross Domestic Product), unemployment (including unemployment rates), national income, price indices, output, consumption, inflation, saving, investment, energy, international trade, and international finance.

Macroeconomics and microeconomics are the two most general fields in economics. The United Nations Sustainable Development Goal 17 has a target to enhance global macroeconomic stability through policy coordination and coherence as part of the 2030 Agenda.# ISO certification in India

Development

Main article: History of macroeconomic thought

Origins

Macroeconomics descended from the once divided fields of business cycle theory and monetary theory. The quantity theory of money was particularly influential prior to World War II. It took many forms, including the version based on the work of Irving Fisher:{\displaystyle M\cdot V=P\cdot Q}

In the typical view of the quantity theory, money velocity (V) and the quantity of goods produced (Q) would be constant, so any increase in money supply (M) would lead to a direct increase in price level (P). The quantity theory of money was a central part of the classical theory of the economy that prevailed in the early twentieth century.# ISO certification in India

Austrian School

Ludwig Von Mises’s work Theory of Money and Credit, published in 1912, was one of the first books from the Austrian School to deal with macroeconomic topics.

Keynes and his followers

Macroeconomics, at least in its modern form, began with the publication of General Theory of Employment, Interest and Money written by John Maynard Keynes. When the Great Depression struck, classical economists had difficulty explaining how goods could go unsold and workers could be left unemployed. In classical theory, prices and wages would drop until the market cleared, and all goods and labor were sold. Keynes offered a new theory of economics that explained why markets might not clear, which would evolve (later in the 20th century) into a group of macroeconomic schools of thought known as Keynesian economics – also called Keynesianism or Keynesian theory.# ISO certification in India

In Keynes’ theory, the quantity theory broke down because people and businesses tend to hold on to their cash in tough economic times – a phenomenon he described in terms of liquidity preferences. Keynes also explained how the multiplier effect would magnify a small decrease in consumption or investment and cause declines throughout the economy. Keynes also noted the role uncertainty and animal spirits can play in the economy.

The generation following Keynes combined the macroeconomics of the General Theory with neoclassical microeconomics to create the neoclassical synthesis. By the 1950s, most economists had accepted the synthesis view of the macroeconomy. Economists like Paul Samuelson, Franco Modigliani, James Tobin, and Robert Solow developed formal Keynesian models and contributed formal theories of consumption, investment, and money demand that fleshed out the Keynesian framework.# ISO certification in India

Monetarism

Milton Friedman updated the quantity theory of money to include a role for money demand. He argued that the role of money in the economy was sufficient to explain the Great Depression, and that aggregate demand oriented explanations were not necessary. Friedman also argued that monetary policy was more effective than fiscal policy; however, Friedman doubted the government’s ability to “fine-tune” the economy with monetary policy. He generally favored a policy of steady growth in money supply instead of frequent intervention.

Friedman also challenged the Phillips curve relationship between inflation and unemployment. Friedman and Edmund Phelps (who was not a monetarist) proposed an “augmented” version of the Phillips curve that excluded the possibility of a stable, long-run tradeoff between inflation and unemployment. When the oil shocks of the 1970s created a high unemployment and high inflation, Friedman and Phelps were vindicated. Monetarism was particularly influential in the early 1980s. Monetarism fell out of favor when central banks found it difficult to target money supply instead of interest rates as monetarists recommended. Monetarism also became politically unpopular when the central banks created recessions in order to slow inflation.# ISO certification in India

New classical

New classical macroeconomics further challenged the Keynesian school. A central development in new classical thought came when Robert Lucas introduced rational expectations to macroeconomics. Prior to Lucas, economists had generally used adaptive expectations where agents were assumed to look at the recent past to make expectations about the future. Under rational expectations, agents are assumed to be more sophisticated. A consumer will not simply assume a 2% inflation rate just because that has been the average the past few years; they will look at current monetary policy and economic conditions to make an informed forecast. When new classical economists introduced rational expectations into their models, they showed that monetary policy could only have a limited impact.

Lucas also made an influential critique of Keynesian empirical models. He argued that forecasting models based on empirical relationships would keep producing the same predictions even as the underlying model generating the data changed. He advocated models based on fundamental economic theory that would, in principle, be structurally accurate as economies changed. Following Lucas’s critique, new classical economists, led by Edward C. Prescott and Finn E. Kydland, created real business cycle (RB C) models of the macro economy.

RB C models were created by combining fundamental equations from neo-classical microeconomics. In order to generate macroeconomic fluctuations, RB C models explained recessions and unemployment with changes in technology instead of changes in the markets for goods or money. Critics of RB C models argue that money clearly plays an important role in the economy, and the idea that technological regress can explain recent recessions is implausible. However, technological shocks are only the more prominent of a myriad of possible shocks to the system that can be modeled. Despite questions about the theory behind RB C models, they have clearly been influential in economic methodology.# ISO certification in India

New Keynesian response

New Keynesian economists responded to the new classical school by adopting rational expectations and focusing on developing micro-founded models that are immune to the Lucas critique. Stanley Fischer and John B. Taylor produced early work in this area by showing that monetary policy could be effective even in models with rational expectations when contracts locked in wages for workers. Other new Keynesian economists, including Olivier Blanchard, Julio Rotemberg, Greg Mankiw, David Romer, and Michael Woodford, expanded on this work and demonstrated other cases where inflexible prices and wages led to monetary and fiscal policy having real effects.

Like classical models, new classical models had assumed that prices would be able to adjust perfectly and monetary policy would only lead to price changes. New Keynesian models investigated sources of sticky prices and wages due to imperfect competition, which would not adjust, allowing monetary policy to impact quantities instead of prices.

By the late 1990s, economists had reached a rough consensus. The nominal rigidity of new Keynesian theory was combined with rational expectations and the RBC methodology to produce dynamic stochastic general equilibrium (DSGE) models. The fusion of elements from different schools of thought has been dubbed the new neoclassical synthesis. These models are now used by many central banks and are a core part of contemporary macroeconomics.

New Keynesian economics, which developed partly in response to new classical economics, strives to provide microeconomic foundations to Keynesian economics by showing how imperfect markets can justify demand management.# ISO certification in India

Macroeconomic models

Aggregate demand–aggregate supply

A traditional AS–AD diagram showing shift in AD and the AS curve becoming inelastic beyond potential output.

The AD-AS model has become the standard textbook model for explaining the macroeconomy. This model shows the price level and level of real output given the equilibrium in aggregate demand and aggregate supply. The aggregate demand curve’s downward slope means that more output is demanded at lower price levels. The downward slope is the result of three effects: the Pigou or real balance effect, which states that as real prices fall, real wealth increases, resulting in higher consumer demand of goods; the Keynes or interest rate effect, which states that as prices fall, the demand for money decreases, causing interest rates to decline and borrowing for investment and consumption to increase; and the net export effect, which states that as prices rise, domestic goods become comparatively more expensive to foreign consumers, leading to a decline in exports.

In the conventional Keynesian use of the AS-AD model, the aggregate supply curve is horizontal at low levels of output and becomes inelastic near the point of potential output, which corresponds with full employment. Since the economy cannot produce beyond the potential output, any AD expansion will lead to higher price levels instead of higher output.

The AD–AS diagram can model a variety of macroeconomic phenomena, including inflation. Changes in the non-price level factors or determinants cause changes in aggregate demand and shifts of the entire aggregate demand (AD) curve. When demand for goods exceeds supply, there is an inflationary gap where demand-pull inflation occurs and the AD curve shifts upward to a higher price level. When the economy faces higher costs, cost-push inflation occurs and the AS curve shifts upward to higher price levels. The AS–AD diagram is also widely used as an instructive tool to model the effects of various macroeconomic policies.# ISO certification in India