Inflation, Deflation & Disinflation
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Inflation is the sustained increase in the average price level of goods/services in an economy
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Deflation occurs when there is a fall in the average price level of goods/services in an economy
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Deflation only occurs when the percentage change in prices falls below zero %
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Disinflation occurs when the average price level increases but at a decreasing rate than before
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These figures demonstrate disinflation: Y1 = 5% Y2 = 4% Y3 = 2%
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Diagram: UK Inflation, Disinflation and Deflation

Causes of Inflation
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An increase in the average prices in an economy can be caused by demand pull inflation or cost push inflation
1. Demand pull inflation
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Demand pull inflation is caused by excess demand in the economy
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Aggregate demand (AD) is the sum of all expenditure in the economy
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AD = Consumption (C) + Investment (I) + Government spending (G) + Net Exports (X-M)
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Diagram: Demand Pull Inflation

Diagram analysis
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If any of the four components of AD increase, there will be a shift to the right of the AD curve from AD1 → AD2
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At the original price (AP1), there is now a condition of excess demand in the economy (extend the dotted line across until it hits the new demand curve to identify the excess demand)
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Prices for goods/services are bid up from AP1 → AP2
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Demand pull inflation has occurred
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If the Central Bank lowers the base rate, there is likely to be increased borrowing by firms and consumers
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This will result in an increase in consumption and investment
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It is likely to lead to a form of demand-pull inflation
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2. Cost push inflation
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Cost push inflation is caused by increases in the costs of production in an economy
Diagram: Cost Push Inflation

Diagram analysis
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If any of the costs of production increase (labour, raw materials etc.), or if there is a fall in productivity, there will be a shift to the left of the SRAS curve from SRAS1→SRAS2
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At the original price (AP1), there is now a condition of excess demand in the economy
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As prices rise, there is a contraction of AD and an extension of SRAS
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Prices for goods/services are bid up from AP1→AP2
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Cost push inflation has occurred
The Quantity Theory of Money
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The Monetarist model, strongly influenced by economists like Milton Friedman, believe that an increase in money supply can lead to inflation, while a decrease can result in deflation
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Monetarists believe that central banks should focus on controlling the money supply to achieve price stability. They argue that a steady and predictable growth rate in the money supply can contribute to stable economic conditions
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Fisher’s equation of exchange MV = PQ and the Quantity Theory of Money is a key component of the monetarist model
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Equation of exchange (MV = PQ)
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M represents money supply in the economy
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V signifies the velocity or speed at which money circulates in the economy. It measures how many times, on average, a unit of currency changes hands in a given time period
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P represents the general price level of goods/services in the economy. It reflects the average prices of a basket of goods
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Q stands for the real output or quantity of goods/services produced in the economy
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All other things being equal, if the velocity of circulation is constant, the quantity theory of money based on Fisher’s equation of exchange, MV=PQ, predicts that an x% increase in the money supply will always cause an x% increase in nominal national income, i.e there will be inflation
The Relationship Between Expectations and Changes in the Price Level
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Expectations refer to individuals’ anticipations of future economic conditions
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Often, if consumers expect prices to fall, they will delay purchases in the hope of purchasing good/services at lower prices
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The delay in consumption then helps prices to fall!
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Often, if consumers expect prices to rise, they will rush to purchase good/services at lower prices before they rise
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The increase in consumption then helps prices to rise!
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Inflation psychology refers to the psychological factors that influence how individuals and businesses anticipate and react to inflation
Types of Inflation Psychology
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Adaptive Expectations |
Rational Expectations |
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The Consequences of Inflation
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The consequences of inflation are different for different stakeholders in the economy
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The consequences are also dependent on the household level of wealth and income
The Impact of Inflation on Different Stakeholders
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Stakeholder |
Explanation of Impact |
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Firms |
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Consumers |
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Government |
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Workers |
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Responses