Unit 4 Inflation and unemployment

4.8 The business cycle model: Demand and supply shocks, and inflation expectations

demand shock
An unexpected or exogenous change in demand. In macroconomics a demand shock means a change in aggregate demand, such as a rise or fall in autonomous consumption, investment, or exports. In microeconomics it refers to an exogenous shift in the demand curve for a particular good. See also: supply shock, exogenous shock.
supply shock, supply-side shock
An unexpected or exogenous change in supply. In macroeconomics a supply shock means a change on the supply side of the economy, such as a rise or fall in oil prices or an improvement in technology. In microeconomics it refers to an exogenous shift in the supply curve for a particular good. See also: demand shock, exogenous shock.

In this section, we first analyse aggregate demand shocks and then supply-side shocks to understand their implications for inflation. To go beyond the snapshot of the first stage of a business cycle, we introduce inflation expectations and shifts in the Phillips curve.

Aggregate demand shocks

Our attention now is on the implications for inflation and unemployment of a negative shock to aggregate demand (often shortened to ‘demand shock’). We therefore hold other things constant: in particular, everything that determines the WS and PS curves, and therefore the supply-side equilibrium.

Fall in planned investment spending: Downward shift of AD curve

Consider the impact of a fall in investment due to a broad-based fall in business confidence about the growth of markets, and therefore about future expected profits. This is typical of business cycle downturns and was the case in the great recession that followed the global financial crisis of 2007–2009 (discussed in more detail in Unit 8).

As shown in Figure 4.17, this can be modelled in the multiplier diagram by the AD curve shifting down. This reduces the level of employment below the supply-side equilibrium and causes cyclical unemployment. We now assume that low demand persists, which is modelled by keeping the AD curve at the ‘low’ level.

Let us assume that the economy was at supply-side equilibrium before the recession occurred. The diagram indicates that an economy at equilibrium would be observed with wage and price inflation of 3% per annum year after year. In the recession caused by the fall in investment, employment has fallen and there is now cyclical unemployment. At the next wage-setting round, HR departments are aware of the greater slack in the labour market. They can employ the smaller required workforce at a lower real wage: this is captured by the negative bargaining gap (as in Figure 4.17c, where the gap is −1%).

Since workers expect prices to rise by 3% as they had done the previous year, and there is a negative bargaining gap of −1%, HR departments are able to settle for a 2% nominal wage increase. This implies a 1% fall in the real wage. Turning to price setting, there has been no change in the competitive conditions faced by firms so, to maximize profits, marketing departments will increase prices by less than the expected inflation rate. If they were to increase prices by a greater amount, the loss of market share to their competitors would outweigh the extra revenue on units sold.

To summarize, the negative shock to investment increases unemployment and lowers both wage and price inflation—in the example, inflation falls from 3% to 2%. This is a movement along the Phillips curve from A to C in Figure 4.19, where only the Phillips curve and multiplier diagrams are shown.

If the investment shock is expected to have a sustained impact on aggregate demand, workers, who are also consumers, will adjust their expectations about how prices will evolve according to their recent experience. Rolling time forward, they will expect prices to rise by 2%. The Phillips curve will shift down and inflation will fall from 2% to 1%. As long as demand remains depressed, the model predicts the presence of cyclical unemployment and falling inflation, with inflation falling from C to D to E (and so on), as the Phillips curve shifts down period by period. The equation introduced in Section 4.7 illustrates this process:

\[\pi_t = \pi_{t-1} + \text{gap}_t\]
There are 2 diagrams. In diagram 1, the horizontal axis displays employment and the vertical axis displays inflation rate, ranging from −2% to 8%. Three upward-sloping, convex lines are labeled Phillips curve at inflation expectation levels 3%, 2%, and 1% respectively. Point A is depicted on the Phillips Curve at an inflation expectation level 3% to represent the employment at supply-side equilibrium where there is no bargaining gap. Its vertical coordinate indicates the expected inflation rate of 3% and horizontal coordinate represents the unemployment level at equilibrium of 7%. Another point labelled C is also shown along the Phillips curve, situated below Point A. Two other points, D and E, are located on the Phillips curves at inflation expectation level 2% and 1% respectively. The horizontal coordinates of the points C, D and E all represent an unemployment level falling short of the equilibrium level, while their vertical coordinate indicate a decreasing inflation rate over times, as specified as 2%, 1% and 0% respectively. In diagram 2, the horizontal axis displays Output (income) Y in billions of € ranging from 0 to 100, and the vertical axis displays Aggregate Demand AD in billions of € ranging from 0 to 100. The coordinates are (Output, Aggregate Demand). There is a 45-degree upward-sloping straight line from the origin , labelled “Y = AD”. Starting at a point above 0 on the vertical axis, there is an upward-sloping straight line with a flatter slope than the 45-degree line denoting the initial aggregate demand function labelled AD(medium). Point A replicates its position from diagram 1, denoting the intersection of the 45-degree line and the AD line. Its horizontal coordinate is marked as Y_{SEE}, representing the output level at supply-side equilibrium, while its vertical coordinate represents the value aggregate demand at equilibrium. Another line labelled AD(low) is illustrated. This line shares the same shape as AD(medium) but is positioned beneath it to represent a recession. AD(low) intersects the 45-degree line at point C, D, and E that are replicated from diagram 1. Those points are situated beneath point A, with the vertical coordinate denoting a lower aggregate demand value. Their horizontal coordinate is labelled as Y_{low}, indicating an output level falling short of the supply-side equilibrium.
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Figure 4.19 Falling inflation in a recession.

A negative aggregate demand shock: There are 2 diagrams. In diagram 1, the horizontal axis displays employment and the vertical axis displays inflation rate, ranging from −2% to 8%. One upward-sloping, convex line is labeled Phillips curve at an inflation expectation level 3%. Point A is depicted on the Phillips Curve to represent the employment at supply-side equilibrium where there is no bargaining gap. Its vertical coordinate indicates the expected inflation rate of 3% and horizontal coordinate represents the unemployment level at equilibrium of 7%. Another point labelled C is also shown along the Phillips curve, situated below Point A. Its vertical coordinate represents a 2% inflation rate, and the horizontal coordinate signifies an unemployment level falling short of the equilibrium level. In diagram 2, the horizontal axis displays Output (income) Y in billions of € ranging from 0 to 100, and the vertical axis displays Aggregate Demand AD in billions of € ranging from 0 to 100. The coordinates are (Output, Aggregate Demand). There is a 45-degree upward-sloping straight line from the origin , labelled “Y = AD”. Starting at a point above 0 on the vertical axis, there is an upward-sloping straight line with a flatter slope than the 45-degree line denoting the initial aggregate demand function labelled AD(medium). Point A replicates its position from diagram 1, denoting the intersection of the 45-degree line and the AD line. Its horizontal coordinate is marked as Y_{SEE}, representing the output level at supply-side equilibrium, while its vertical coordinate represents the value aggregate demand at equilibrium. Another line labelled AD(low) is illustrated. This line shares the same shape as AD(medium) but is positioned beneath it to represent a recession. AD(low) intersects the 45-degree line at point C that is replicated from diagram 1. Ponit C is situated beneath point A, with the vertical coordinate denoting a lower aggregate demand value. Its horizontal coordinate is labelled as Y_{low}, indicating an output level falling short of the supply-side equilibrium.
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A negative aggregate demand shock

A negative aggregate demand shock shifts the AD curve down from AD (medium) to AD (low). Output falls from its supply-side equilibrium level, \(Y_\text{SSE}\), to \(Y_\text{low}\) (bottom panel). This shock moves the economy along the Phillips curve from point A to point C, where inflation is now 2% (top panel).

Inflation expectations change: There are 2 diagrams. In diagram 1, the horizontal axis displays employment and the vertical axis displays inflation rate, ranging from −2% to 8%. One upward-sloping, convex line is labeled Phillips curve at an inflation expectation level 3%. Point A is depicted on the Phillips Curve to represent the employment at supply-side equilibrium where there is no bargaining gap. Its vertical coordinate indicates the expected inflation rate of 3% and horizontal coordinate represents the unemployment level at equilibrium of 7%. Another point labelled C is also shown along the Phillips curve, situated below Point A. Its vertical coordinate represents a 2% inflation rate, and the horizontal coordinate signifies an unemployment level falling short of the equilibrium level. In diagram 2, the horizontal axis displays Output (income) Y in billions of € ranging from 0 to 100, and the vertical axis displays Aggregate Demand AD in billions of € ranging from 0 to 100. The coordinates are (Output, Aggregate Demand). There is a 45-degree upward-sloping straight line from the origin , labelled “Y = AD”. Starting at a point above 0 on the vertical axis, there is an upward-sloping straight line with a flatter slope than the 45-degree line denoting the initial aggregate demand function labelled AD(medium). Point A replicates its position from diagram 1, denoting the intersection of the 45-degree line and the AD line. Its horizontal coordinate is marked as Y_{SEE}, representing the output level at supply-side equilibrium, while its vertical coordinate represents the value aggregate demand at equilibrium. Another line labelled AD(low) is illustrated. This line shares the same shape as AD(medium) but is positioned beneath it to represent a recession. AD(low) intersects the 45-degree line at point C that is replicated from diagram 1. Ponit C is situated beneath point A, with the vertical coordinate denoting a lower aggregate demand value. Its horizontal coordinate is labelled as Y_{low}, indicating an output level falling short of the supply-side equilibrium. In diagram 1, an additional Phillips curve reflecting a 2% inflation expectation is illustrated. This curve mirrors the original one in shape but is positioned below it. Point D, located directly beneath point C on the new Phillips curve, corresponds to the same unemployment level, maintaining the same horizontal coordinate. However, its vertical coordinate indicates a decreased inflation rate of 1%. In diagram 2, point D, replicated from diagram 1, aligns precisely with point C in the same position.
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Inflation expectations change

Inflation expectations change from 3% to 2%, which shifts the Phillips curve downwards (point C to point D, top panel). At the current level of output, inflation is now 1%.

The Phillips curve shifts downwards again: There are 2 diagrams. In diagram 1, the horizontal axis displays employment and the vertical axis displays inflation rate, ranging from −2% to 8%. One upward-sloping, convex line is labeled Phillips curve at an inflation expectation level 3%. Point A is depicted on the Phillips Curve to represent the employment at supply-side equilibrium where there is no bargaining gap. Its vertical coordinate indicates the expected inflation rate of 3% and horizontal coordinate represents the unemployment level at equilibrium of 7%. Another point labelled C is also shown along the Phillips curve, situated below Point A. Its vertical coordinate represents a 2% inflation rate, and the horizontal coordinate signifies an unemployment level falling short of the equilibrium level. In diagram 2, the horizontal axis displays Output (income) Y in billions of € ranging from 0 to 100, and the vertical axis displays Aggregate Demand AD in billions of € ranging from 0 to 100. The coordinates are (Output, Aggregate Demand). There is a 45-degree upward-sloping straight line from the origin , labelled “Y = AD”. Starting at a point above 0 on the vertical axis, there is an upward-sloping straight line with a flatter slope than the 45-degree line denoting the initial aggregate demand function labelled AD(medium). Point A replicates its position from diagram 1, denoting the intersection of the 45-degree line and the AD line. Its horizontal coordinate is marked as Y_{SEE}, representing the output level at supply-side equilibrium, while its vertical coordinate represents the value aggregate demand at equilibrium. Another line labelled AD(low) is illustrated. This line shares the same shape as AD(medium) but is positioned beneath it to represent a recession. AD(low) intersects the 45-degree line at point C that is replicated from diagram 1. Ponit C is situated beneath point A, with the vertical coordinate denoting a lower aggregate demand value. Its horizontal coordinate is labelled as Y_{low}, indicating an output level falling short of the supply-side equilibrium. In diagram 1, an additional Phillips curve reflecting a 2% inflation expectation is illustrated. This curve mirrors the original one in shape but is positioned below it. Point D, located directly beneath point C on the new Phillips curve, corresponds to the same unemployment level, maintaining the same horizontal coordinate. However, its vertical coordinate indicates a decreased inflation rate of 1%. In diagram 2, point D, replicated from diagram 1, aligns precisely with point C in the same position. In diagram 1, another additional Phillips curve reflecting a 1% inflation expectation is illustrated. This curve mirrors the other Phillips curves in shape but is positioned below them. Point E, located directly beneath point D on the new Phillips curve, corresponds to the same unemployment level, maintaining the same horizontal coordinate. However, its vertical coordinate indicates a decreased inflation rate of 0%. In diagram 2, point E, replicated from diagram 1, aligns precisely with point C and D in the same position.
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The Phillips curve shifts downwards again

If the AD curve remains at AD (low) next year, inflation expectations further adjust downwards to 1% and the Phillips curve shifts downwards again. This process will repeat itself as long as output remains at its current level.

At a lower level of aggregate demand (a recession), there is higher unemployment, a negative bargaining gap, and inflation is lower. The model predicts falling inflation (that is, disinflation) for as long as a negative bargaining gap persists and expected inflation falls, shifting the Phillips curve down. And in the opposite case of a boom, we predict rising inflation period by period for as long as a positive bargaining gap persists and expected inflation rises. The unpopularity of rising inflation and of falling inflation when it threatens to turn into deflation leads policy makers to intervene. We discuss how they do so in Unit 5.

Supply-side shocks

In our next experiment, we hold the demand side of the economy constant. The AD curve in the multiplier diagram remains unchanged and since output and employment are entirely determined by the demand side, they do not change either. At this level of output and employment, we analyse what happens to inflation when there is a change on the supply side.

Increased market power of firms: Downward shift of PS curve

This is an inflationary shock.

protectionist policy
Measures taken by a government to limit trade; in particular, to reduce the amount of imports in the economy. These are designed to protect local industries from external competition. They can take different forms, such as taxes on imported goods or import quotas.

The new scenario is that the government adopts protectionist policies, which make it more difficult for foreign firms to enter its markets. Competition is therefore less intense in domestic markets, which means firms can charge higher markups on their costs. From Unit 1, we know that this shifts the PS curve downward, and using the term we introduced in this unit, it opens up a positive bargaining gap at the pre-existing level of employment. Another way of putting this, which is also shown in Figure 4.20a, is that while employment remains unchanged, the supply-side equilibrium (SSE) has shifted from point A to point C at lower employment, \(N′_\text{SSE}\).

In the diagram, the horizontal axis shows employment and the vertical axis shows real wage. Coordinates are (employment, real wage). The vertical line at the end of the horizontal axis is labeled labour force. The diagram displays two horizontal lines: one labelled ‘PS curve’ and the other ‘PS curve with higher markup’, with the former positioned above the latter. The initial PS curve has a vertical coordinate of 100, indicating the original real wage level, while the PS curve with higher markup has a smaller vertical coordinate of 98. An upward-sloping, convex curve labelled ‘WS curve’ intersects with both horizontal lines. The points of intersection between the WS curve and the two PS curves are labelled as point A and C respectively. Point A’s horizontal coordinate indicates the employment level at the initial equilibrium, N_{SSE}, whereas that of point C indicates the employment level at the new equilibrium with a higher markup, N_{SSE}’. The difference between A’s and C’s vertical coordinate indicates a bargaining gap of 2%.
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Figure 4.20a A negative supply-side shock (higher markup) opens up a bargaining gap at the initial equilibrium employment level.

Figure 4.20b combines the supply-side and the multiplier diagrams to highlight the situation following the shock. The economy is at point A in both panels and we assume that aggregate demand continues to remain unchanged as the implications for inflation unfold. From the multiplier model, the level of aggregate demand determines the level of output at \(Y_0\) and this fixes employment at \(N_0\) throughout.

There are 2 diagrams. In diagram 1, the horizontal axis shows employment and the vertical axis shows real wage. Coordinates are (employment, real wage). The vertical line at the end of the horizontal axis is labeled labour force. The diagram displays two horizontal lines: one labelled ‘PS curve’ and the other ‘PS curve with higher markup’, with the former positioned above the latter. The initial PS curve has a vertical coordinate of 100, indicating the original real wage level, while the PS curve with higher markup has a smaller vertical coordinate of 98. An upward-sloping, convex curve labelled ‘WS curve’ intersects with both horizontal lines. The points of intersection between the WS curve and the two PS curves are labelled as point A and C respectively. Point A’s horizontal coordinate indicates the employment level at the initial equilibrium, N_0, whereas that of point C indicates the employment level at the new equilibrium with a higher markup, N’_{SSE}. The difference between A’s and C’s vertical coordinate indicates a bargaining gap of 2%. In diagram 2, the horizontal axis displays Output (income) Y in billions of € ranging from 0 to 100 and the vertical axis displays Aggregate Demand AD in billions of € ranging from 0 to 100. The coordinates are (Output, Aggregate Demand). There is a 45-degree upward-sloping straight line from the origin , labelled ‘Y = AD’. Starting at a point above 0 on the vertical axis, there is an upward-sloping straight line with a flatter slope than the 45-degree line denoting the initial aggregate demand function labelled AD(medium). Point A replicates its position from diagram 1, denoting the intersection of the 45-degree line and the AD line. Its horizontal coordinate is marked as Y_0, representing the output level at supply-side equilibrium, while its vertical coordinate represents the value aggregate demand at equilibrium.
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Figure 4.20b A negative supply-side shock (higher markup) and unchanged aggregate demand.

The next step is to introduce inflation and the Phillips curve. Since aggregate demand and employment are fixed, we drop the multiplier panel and replace it with the Phillips curve diagram.

There are 2 diagrams. In diagram 1, the horizontal axis shows employment and the vertical axis shows real wage. Coordinates are (employment, real wage). The vertical line at the end of the horizontal axis is labeled labour force. The horizontal line is labelled ‘PS curve with higher markup’, with a smaller vertical coordinate of 98. An upward-sloping, convex curve labelled ‘WS curve’ intersects with the PS curve, labelled as point C. Another point A is depicted, whose horizontal coordinate indicates the employment level at the initial equilibrium, N_0, whereas that of point C indicates the employment level at the new equilibrium with a higher markup, N’_{SSE}. The difference between A’s and C’s vertical coordinate indicates a bargaining gap of 2%. In diagram 2, the horizontal displays represents employment, and the vertical axis displays inflation rate in percentage from −2% to 12%. The coordiantes are (Employment, Inflation rate). There are three convex, upward-sloping curves of the same shape, each labelled ‘Phillips curve’. The topmost curve indicates the new supply-side equilibrium with an expected inflation of 5%, the middle one represents the new supply-side equilibrium with an expected inflation of 3%, and the bottommost one depicts the original supply-side equilibrium with an expected inflation of 3%. Point A, replicated from diagram 1, is located on the Phillips curve representing the original supply-side equilibrium, with horizontal coordinates denoting N_0 and vertical coordinates denoting the 3% inflation rate. Points D and E are positioned vertically above on the middle and top Phillips curves respectively. Their horizontal coordinates remain at N_0 but with higher vertical coordinates, each representing 5% and 7% inflation rates respectively.
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Figure 4.20c Consequences for inflation of a negative supply-side shock (a higher markup shifts the PS curve down and the Phillips curve up).

The new supply-side equilibrium (at C in the upper panel) has a different and higher Phillips curve. In the example, the reduction in competition facing firms enables them to increase their prices by 2% on top of the 3% that covers the rise in wages. So at each level of employment, inflation is 2% higher than before. The Phillips curve shifts up by 2%. The economy moves from its initial position at point A with employment of \(N_0\) and inflation of 3% to point D with inflation of 5%. Expected inflation is still 3%. The new Phillips curve is labelled (new SSE, expected inflation = 3%); on this curve, inflation equals expected inflation at point C, the new supply-side equilibrium.

Behind the shift in the Phillips curve is the behaviour of wage and price setters. Prices increased by 5% while workers were expecting a 3% rise (point B). This reduces the real wage by 2%: the real wage on the new PS curve is below the wage on the WS curve at the level of employment \(N_0\). While the owners are happy with the higher price that the marketing department can now charge, workers are unhappy with the fall in the real wage.

At the next wage round, expected inflation is 5% and the Phillips curve shifts again, to the one labelled (new SSE, expected inflation = 5%). To encourage workers to put in the required effort, the HR department will raise the nominal wage by another 2% (to 7%).

Will it end there? No. The nominal wage increase has raised the cost of production to firms by 7% and they will use this as the basis of their markup pricing, leading to a further increase in prices (by 7%) and a fall in the real wage, which the HR department will have to correct the following year by again raising the nominal wage (by \(7 + 2 = 9\%\)). Each year, there will be another rise in inflation of 2%.

In the absence of policy intervention, the economy is characterized by an inflationary wage–price spiral initiated by the weaker conditions for competition in the market for goods and services.

Question 4.7 Choose the correct answer(s)

Figure 4.20a depicts the model of the supply side of the economy.

Suppose now that the government adopts policies that make it difficult for foreign firms to enter its markets. Assume that the level of employment and the labour force remain constant. Read the following statements regarding inflation and choose the correct one(s).

  • Firms can now charge a higher markup on their costs, raising the price-setting curve.
  • At the lower real wage, it is more difficult to recruit and motivate workers. Therefore nominal wages are increased, described by an upward shift in the wage-setting curve.
  • If firms are able to continue setting prices to reflect the new higher markup, the rate of inflation rises after each wage round, lowering the real wage to the (lower) price-setting curve.
  • At each wage round, wage inflation goes up, increasing the real wage temporarily to the level on the wage-setting curve.
  • A higher markup implies a downward shift in the price-setting curve.
  • Nominal wages rise because the real wage is below the wage-setting curve at the unchanged unemployment rate. The wage-setting curve does not shift.
  • This is correct. Firms raise their prices by the increase in wages, returning the real wage to the (lower) PS curve.
  • This is correct. As long as employment and the WS curve stay fixed, workers will negotiate a wage rise to the real wage on the WS curve. However, the real wage will be reduced to the level of the PS curve when marketing departments set prices.

Increased union bargaining power: Upward shift of WS curve

This is a second type of inflationary supply shock.

Still holding the demand side of the economy and employment fixed, we next analyse what happens to inflation when there is an upward shift of the WS curve, because unions become stronger, or withdraw bargaining restraint as described in Unit 2. When the WS curve shifts up, there is a new supply-side equilibrium at lower employment and higher unemployment as shown in Figure 4.21: there is now a bargaining gap at the pre-existing level of employment, \(N_0\).

There are 2 diagrams. In diagram 1, the horizontal axis shows employment and the vertical axis shows real wage. Coordinates are (employment, real wage). The vertical line at the end of the horizontal axis is labeled labour force. The horizontal line is labelled ‘PS curve’ with a vertical coordinate of 100, indicating the initial real wage level. There are two upward-sloping, convex curves: one labelled ‘WS curve’ positioned below, and the other labelled ‘WS curve (higher unemployment benefit)’ situated above. Point A marks the intersection between ‘PS curve’ and ‘WS curve’, with its horizontal coordinate indicating the supply-side equilibrium, N_0. At N_0, the corresponding real wage is 102. The vertical distance between A’s vertical coordinate and the WS curve with a higher unemployment benefit implies a 2% bargaining gap. In diagram 2, the horizontal displays represents employment, and the vertical axis displays inflation rate in percentage from −2% to 12%. The coordiantes are (Employment, Inflation rate). There are three convex, upward-sloping curves of the same shape, each labelled ‘Phillips curve’. The topmost curve indicates the new supply-side equilibrium with an expected inflation of 5%, the middle one represents the new supply-side equilibrium with an expected inflation of 3%, and the bottommost one depicts the original supply-side equilibrium with an expected inflation of 3%. Point A, replicated from diagram 1, is located on the Phillips curve representing the original supply-side equilibrium, with horizontal coordinates denoting N_0 and vertical coordinates denoting the 3% inflation rate. Points D and E are positioned vertically above on the middle and top Phillips curves respectively. Their horizontal coordinates remain at N_0 but with higher vertical coordinates, each representing 5% and 7% inflation rates respectively.
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Figure 4.21 Consequences for inflation of a supply-side shock that shifts the WS curve up.

In this example, the increase in union bargaining power means that HR departments must pay an additional 2% in wage increases on top of the 3% rise in wages required to cover expected inflation. This takes the economy from its initial position at point A with employment of \(N_0\) and inflation of 3% to point B with inflation of 5%. Given that their costs have risen by 5%, the marketing departments in firms across the economy raise prices by 5%. With 5% inflation, the Phillips curve shifts up as shown.

Following the logic in the previous example, inflation expectations will be updated each year, and the Phillips curve will shift upwards. Each year there will be another rise in inflation of 2%. In the absence of policy intervention, the economy is characterized by a wage–price spiral initiated in this case by increased union power.

An upward shift in the WS curve could come about for other reasons, such as improved generosity of unemployment benefits. Although the initial cause is different, this also has the effect of strengthening the position of workers in the labour market, and the effect on wages and prices would be the same.

These two examples show that inflation may result from:

  • An increase in the market power of firms over their consumers: This is caused by a reduction in competition, which allows firms to charge a higher markup. It is a downward shift of the price-setting curve.
  • An improvement in the position of workers in the labour market: This allows them to get a higher wage offer in return for working hard. It is an upward shift of the wage-setting curve.

Starting at this inflation-stabilizing rate of unemployment, increased inflation can occur for two reasons:

  • An inflationary demand shock increases employment above the supply-side equilibrium, and therefore introduces a bargaining gap which raises inflation.
  • An inflationary supply shock changes the supply-side equilibrium—either because the PS curve shifts down, lowering the real wage, or because the WS curve shifts up, increasing the real wage workers want (but do not get). As a result, a bargaining gap opens up even if employment remains unchanged.

Question 4.8 Choose the correct answer(s)

Figure 4.21 (top panel) depicts the model of the supply side of the economy. Suppose that a supply shock enables workers to obtain higher wage offers from firms. Read the following statements and choose the correct option(s).

  • An increase in wage offers can result from an improvement in the technology through which managers can monitor ‘time on task’ for those working remotely.
  • The upward-sloping WS curve reflects rising better alternative options for workers in the labour market.
  • After an upward shift in the WS curve, firms adjust their prices, which shifts the PS curve.
  • After the initial increase in wage offers, both wage and price inflation rise.
  • Improved monitoring of ‘time on task’ increases the risk of being caught shirking and fired, and so reduces the employment rent which workers need to receive to deliver the effort required, and shifts the WS curve down.
  • This is correct. A higher wage must be offered to recruit and motivate workers as the unemployment rate falls.
  • The adjustment of prices changes the real wage; it does not shift the PS curve.
  • This is correct. Wage and price inflation rise because there is now a bargaining gap. Inflation will rise by expected inflation plus the bargaining gap as shown by the Phillips curve.

Exercise 4.9 Modelling supply-side and demand-side shocks

Starting with the scenario in Figure 4.19, draw WS–PS, Phillips curve, and AD diagrams to illustrate and explain what happens after the following shocks:

  1. a positive shock to investment
  2. an increase in market competition.

Exercise 4.10 Wars, pandemics, and inflation

Read the VoxEU article ‘Inflation in the aftermath of wars and pandemics’ (written in April 2021), which uses data from the fourteenth century to compare the behaviour of inflation after wars and after pandemics.

  1. Use the WS–PS diagram, Phillips curve diagram, and AD model to interpret the findings reported in Figure 3, assuming there is no change to the supply-side equilibrium. Draw appropriate diagrams to illustrate your answer.
  2. The analysis in Question 1 assumed no changes to the supply-side equilibrium. Use the information in the article to comment on how reasonable this assumption is.