Tag: hysteresis

To make a sensible comparison of one year’s national income generated from the production of goods and services with another we need to take inflation into account. Changes in inflation-adjusted GDP represent changes in the volume of production of a country’s goods and services: in other words, the real value of goods and services. We revisit the blog written back in April 2019, prior the pandemic, to show how changes in real GDP evidence what we may refer to as the twin characteristics of economic growth: positive long-term growth but with fluctuating short-term rates of growth.

Real and nominal GDP

The nominal or current-price estimate for UK Gross Domestic Product in 2020 is £2.156 trillion. It is the value of output produced within the country in 2020. This was a fall of 4.4 per cent on the £2.255 trillion recorded in 2019. These values make no adjustment for inflation and therefore reflect the prices of output that were prevailing at the time.

Chart 1 shows current-price estimates of GDP from 1950 when the value of GDP was estimated at £12.7 billion. The increase to £2.156 trillion in 2020 amounts to a proportionate increase of almost 170 times, a figure that rises to 211 times if we compare the 1950 value with the latest IMF estimate for 2025 of £2.689 trillion. However, if we want to make a more meaningful comparison of the country’s national income by looking at the longer-term increase in the volume of production, we need to adjust for inflation. (Click here to download a PowerPoint copy of the chart.)

Long-term growth in real GDP

If we measure GDP at constant prices, we eliminate the effect of inflation. To construct a constant-price series for GDP a process known as chain-linking is used. This involves taking consecutive pairs of years, e.g. 2020 and 2021, and estimating what GDP would be in the most recent year (in this case, 2021) if the previous year’s prices (i.e. 2020) had continued to prevail. By calculating the percentage change from the previous year’s GDP value we have an estimate of the volume change. If this is repeated for other pairs of years, we have a series of percentage changes that capture the volume changes from year-to-year. Finally, a reference year is chosen and the percentage changes are applied backwards and forwards from the nominal GDP value for the reference year – the volume changes forwards and backwards from this point.

In effect, a real GDP series creates a quantity measure in monetary terms. Chart 1 shows GDP at constant 2019 prices (real GDP) alongside GDP at current prices (nominal GDP). Consider first the real GDP numbers for 1950 and 2020. GDP in 1950 at 2019 prices was £410.1 billion. This is higher than the current-price value because prices in 2019 (the reference year) were higher than those in 1950. Meanwhile, GDP in 2020 when measured at 2019 prices was £2.037 trillion. This constant-price value is smaller than the corresponding current-price value because prices in 2019 where lower than those in 2020.

Between 1950 and 2020 real GDP increased 5.0 times. If we extend the period to 2025, again using the latest IMF estimates, the increase is 5.9 times. Because we have removed the effect of inflation, the real growth figure is much lower than the nominal growth figure. Crucially, what we are left with is an indicator of the long-term growth in the volume of the economy’s output and hence an increase in national income that is backed up by an increase in production. Whereas nominal growth rates are affected both by changes in volumes and prices, real growth rates reflect only changes in volumes.

The upward trajectory observed in constant-price GDP is therefore evidence of positive longer-term growth. This is one of the twin characteristics of growth.

Short-term fluctuations in the growth of real GDP

The second characteristic is fluctuations in the rate of growth from period to period. We can see this second characteristic more clearly by plotting the percentage change in real GDP from year to year.

Chart 2 shows the annual rate of growth in real GDP each year since 1950. From it, we see the inherent instability that is a key characteristic of the macroeconomic environment. This instability is, of course, mirrored in the output path of real GDP in Chart 1, but the annual rates of growth show the instability more clearly. We can readily see the impact on national output of the global financial crisis and the global health emergency.

In 2009, constant-price GDP in the UK fell by 4.25 per cent. Then, in 2020, constant-price GDP and, hence, the volume of national output fell by 9.7 per cent, as compared to a 4.4 per cent fall in current-price GDP that we identified earlier. These global, ‘once-in-a-generation’ shocks are stark examples of the instability that characterises economies and which generate the ‘ups and downs’ in an economy’s output path, known more simply as ‘the business cycle’. (Click here to download a PowerPoint copy of the chart.)

Determinants of long-and short-term growth

The twin characteristics of growth can be seen simultaneously by combining the output path captured by the levels of real GDP with the annual rates of growth. This is shown in Chart 3. The longer-term growth seen in the economy’s output path is generally argued to be driven by the quantity and quality of the economy’s resources, and their effectiveness when combined in production. In other words, it is the supply-side that determines the trajectory of the output path over the longer term. (Click here to download a PowerPoint copy of the chart.)

However, the fluctuations we observe in short-term growth rates tend to reflect impulses that affect the ability and or willingness of producers to supply (supply-side shocks) and purchasers to consume (demand-side shocks). These impulses are then propagated and their effects, therefore, transmitted through the economy.

Effects of the pandemic

The pandemic is unusual in that the health intervention measures employed by governments around the world resulted in simultaneous negative aggregate demand and aggregate supply shocks. Economists were particularly concerned that the magnitude of these impulses and their propagation had the potential to generate scarring effects and hence negative hysteresis effects. The concern was that these would affect the level of real GDP in the medium-to-longer term and, hence, the vertical position of the output path, as well as the longer-term rate of growth and, hence, the steepness of the output path.

The extent of these scarring effects continues to be debated. The ability of businesses and workers to adapt their practices, the extraordinary fiscal and monetary measures that were undertaken in many countries, and the roll-out of vaccines programmes, especially in advanced economies, have helped to mitigate some of these effects. For example, the latest IMF forecasts for output in the USA in 2024 are over 2 per cent higher than those made back in October 2019.

Scarring effects are, however, thought to be an ongoing issue in the UK. The IMF is now expecting output in the UK to be nearly 3 per cent lower than it originally forecast back in October 2019. Therefore, whilst UK output is set to recover, scarring effects on the UK economy will mean that the output path traced out by real GDP will remain, at least in the medium term, vertically lower than was expected before the pandemic.

Data and Reports



  1. What do you understand by the term ‘macroeconomic environment’? What data could be used to describe the macroeconomic environment?
  2. When a country experiences positive rates of inflation, which is higher: nominal economic growth or real economic growth?
  3. Does an increase in nominal GDP mean a country’s production has increased? Explain your answer.
  4. Does a decrease in nominal GDP mean a country’s production has decreased? Explain your answer.
  5. Why does a change in the growth of real GDP allow us to focus on what has happened to the volume of production?
  6. What does the concept of the ‘business cycle’ have to do with real rates of economic growth?
  7. When would falls in real GDP be classified as a recession?
  8. Distinguish between the concepts of ‘short-term growth rates’ and ‘longer-term growth’.
  9. What do you understand by the term hysteresis? By what means can hysteresis effects be generated?
  10. Discuss the proposition that the pandemic could have a positive effect on longer-term growth rates because of the ways that people and business have had to adapt.

One of the major economic concerns about the COVID-19 pandemic has been the likely long-term scarring effects on economies from bankruptcies, a decline in investment, lower spending on research and development, a loss of skills, discouragement of workers, disruption to education, etc. The result would be a decline in potential output or, at best, a slower growth. These persistent effects are known as ‘hysteresis’ – an effect that persists after the original cause has disappeared.

In a speech by Dave Ramsden, the Bank of England’s Deputy Governor for Markets & Banking, he argued that, according to MPC estimates, the pandemic will have caused a loss of potential output of 1.75%. This shortfall may seem small at first sight, so does it matter? According to Ramsden:

The answer is definitely yes for two reasons. First, a 1¾% shortfall as a share of annual GDP for the UK … represents roughly £39 billion – for context, that’s about half of the education budget. And second, that 1¾% represents a permanent shortfall, or at least a very persistent one, on top of the impact of the immediate downturn. If you lose 1¾% of GDP every year for ten years, then in total you have lost 17.5% of one year’s GDP, or around £390bn in 2019 terms

However, as the IMF blog linked below argues, there may be positive supply-side effects which outweigh these scarring effects, causing a net rise in potential GDP growth. There are two possible reasons for this.

The first is that the pandemic may have hastened the process of digitalisation and automation. Examples include ‘video conferencing and file sharing applications to drones and data-mining technologies’. According to evidence from a sample of 15 countries cited in the blog, a 10% rise in such intangible capital investment is associated with about a 4½% rise in labour productivity. ‘As COVID-19 recedes, the firms which invested in intangible assets, such as digital technologies and patents may see higher productivity as a result.’

The second is a reallocation of workers and capital to more productive sectors. Firms in some sectors, such as leisure, hospitality and retail, have relatively low labour productivity. Many parts of these industries have declined during the pandemic, especially those with high labour intensity. At the same time, there has been a rise in employment in firms where output per worker is higher. Such sectors include e-commerce and those where remote working is possible. The greater the reallocation from low labour-productivity to high labour-productivity sectors, the more will overall labour productivity rise and hence the more will potential output increase.

The size of these two effects will depend to a large extent on expectations, incentives and government policy. The blog cites four types of policy that can help investment and reallocation.

  • Improved insolvency and restructuring procedures to enable capital in failed firms to be reallocated to sectors with potential for growth.
  • Promoting competition to enable the exit and entry of firms into expanding sectors and to prevent powerful firms from blocking the process.
  • Refocusing policy from retaining labour in existing jobs to reskilling workers for new jobs, thereby improving labour mobility from declining to expanding sectors.
  • Addressing financial bottlenecks, so as to ensure adequate access to financing for viable firms.

Whether there will be a net increase or decrease in productivity from the pandemic very much depends on the extent to which firms and workers are able and willing to take advantage of new opportunities and the extent to which government supports investment in and reallocation to high-productivity sectors.

Blogs, articles and speeches


  1. Can actual economic growth be greater than potential economic growth (a) in the short run; (b) in the long run?
  2. Give some example of scarring effects from the COVID-19 pandemic.
  3. What effects might short-term policies to tackle the recession caused by the pandemic have on longer-term potential economic growth?
  4. What practical policies could governments adopt to encourage the positive supply-side effects of the pandemic? To what extent would these policies have negative short-term effects?
  5. Why might (endogenous) financial crises result in larger and more persistent reductions in potential output than exogenous crises, such as a pandemic or a war?
  6. Distinguish between interventionist and market-orientated supply-side policies to encourage the reallocation of labour and capital to higher-productivity sectors.

In a series of five podcasts, broadcast on BBC Radio 4 in the first week of January 2021, Amol Rajan and guests examine different aspects of inequality and consider the concept of fairness.

As the notes to the programme state:

The pandemic brought renewed focus on how we value those who have kept shelves stacked, transport running and the old and sick cared for. So is now the time to bring about a fundamental shift in how our society and economy work?

The first podcast, linked below, examines the distribution of wealth in the UK and how it has changed over time. It looks at how rising property and share prices and a lightly taxed inheritance system have widened inequality of wealth.

It also examines rising inequality of incomes, a problem made worse by rising wealth inequality, the move to zero-hour contracts, gig working and short-term contracts, the lack of social mobility, austerity following the financial crisis of 2007–9 and the lockdowns and restrictions to contain the coronavirus pandemic, with layoffs, people put on furlough and more and more having to turn to food banks.

Is this rising inequality fair? Should fairness be considered entirely in monetary terms, or should it be considered more broadly in social terms? These are issues discussed by the guests. They also look at what policies can be pursued. If the pay of health and care workers, for example, don’t reflect their value to our society, what can be done to increase their pay? If wealth is very unequally distributed, should it be redistributed and how?

The questions below are based directly on the issues covered in the podcast in the order they are discussed.



  1. In what ways has Covid-19 been the great ‘unequaliser’?
  2. What scarring/hysteresis effects are there likely to be from the pandemic?
  3. To what extent is it true that ‘the more your job benefits other people, the less you get paid’?
  4. How has the pandemic affected inter-generational inequality?
  5. How have changes in house prices skewed wealth in the UK over the past decade?
  6. How have changes in the pension system contributed to inter-generational inequality?
  7. How has quantitative easing affected the distribution of wealth?
  8. Why is care work so poorly paid and how can the problem be addressed?
  9. How desirable is the pursuit of wealth?
  10. How would you set about defining ‘fairness’?
  11. Is a mix of taxation and benefits the best means of tackling economic unfairness?
  12. How would you set about deciding an optimum rate of inheritance tax?
  13. How do you account for the growth of in-work poverty?
  14. In what ways could wealth be taxed? What are the advantages and disadvantages of such taxes?

Boris Johnson gave a speech on 30 June outlining his government’s approach to recovery from the sharpest recession on record. With the slogan ‘Build, build, build’, he said that infrastructure projects were the key to stimulating the economy. Infrastructure spending is a classic Keynesian response to recession as it stimulates aggregate demand allowing slack to be taken up, while also boosting aggregate supply, thereby allowing recovery in output while increasing potential national income.

A new ‘New deal’

He likened his approach to that of President Franklin D Roosevelt’s New Deal. This was a huge stimulus between 1933 and 1939 in an attempt to lift the US economy out of the Great Depression. There was a massive programme of government spending on construction projects, such as hospitals, schools, roads, bridges and dams, including the Hoover Dam and completing the 113-mile Overseas Highway connecting mainland Florida to the Florida Keys. Altogether, there were 34 599 projects, many large-scale. In addition, support was provided for people on low incomes, the unemployed, the elderly and farmers. Money supply was expanded, made possible by leaving the Gold Standard in 1934.

There was some debate as to whether the New Deal could be classed as ‘Keynesian’. Officially, the administration was concerned to achieve a balanced budget. However, it had a separate ’emergency budget’, from which New Deal spending was financed. According to estimates by the Federal Reserve Bank of St Louis, the total extra spending amounted to nearly 40% of US GDP as it was in 1929.

By comparison with the New Deal, the proposals of the Johnson government are extremely modest. Mostly it amounts to bringing forward spending already committed. The total of £5 billion is just 0.2% of current UK GDP.

Focusing on jobs

A recent report published by the Resolution Foundation, titled ‘The Full Monty‘, argues that as the Job Retention Scheme, under which people have been furloughed on 80% pay, is withdrawn, so unemployment is set to rise dramatically. The claimant count has already risen from 1.2m to 2.8m between March and May with the furlough scheme in place.

Policy should thus focus on job creation, especially in those sectors likely to experience the largest rise in unemployment. Such sectors include non-food retail, hospitality (pubs, restaurants, hotels, etc.), public transport, the arts, entertainment and leisure and a range of industries servicing these sectors. What is more, many of the people working in these sectors are young and low paid. Many will find it difficult to move to jobs elsewhere – partly because of a lack of qualifications and partly because of a lack of alternative jobs. The rising unemployment will raise inequality.

The Resolution Foundation report argues that policy should be focused specifically on job creation.

Policy makers should act now to minimise outflows from the hard-hit sectors – a wage subsidy scheme or a National Insurance cut in those sectors would reduce labour costs and discourage redundancies. Alongside this, the Government must pursue radical action to create jobs across the country, such as in social care and housing retrofitting, and ramp up support for the unemployed.

Dealing with hyteresis

The economy is set to recover somewhat as the lockdown is eased, but it is not expected to return to the situation before the pandemic. Many jobs will be lost permanently unless government support continues.

Even then, many firms will have closed and others will have reassessed how many workers they need to employ and whether less labour-intensive methods would be more profitable. They may take the opportunity to consider whether technology, such as AI, can replace labour; or they may prefer to employ cheap telecommuters from India or the Philippines rather than workers coming into the office.

Policies to stimulate recovery will need to take these hysteresis effects into account if unemployment is to fall back to pre-Covid rates.





  1. What are the arguments for and against substantial increased government expenditure on infrastructure projects?
  2. Should the UK government spend more or less on such projects than the amount already pledged? Justify your answer.
  3. What are the arguments for and against directing all extra government expenditure towards green projects?
  4. Look through the Resolution Foundation report and summarise the findings of each of its sections.
  5. What are the arguments for and against directing all extra government expenditure towards those sectors where there is the highest rate of job losses?
  6. What form could policies to protect employment take?
  7. How should the success of policies to generate employment be measured?
  8. What form does hysteresis play on the post-Covid-19 labour market? What four shocks mean that employment will not simply return to the pre-Covid situation?

In the blog post, Global warning, we looked at the use of unconventional macroeconomic policies to deal with the slow pace of economic growth around the world. One of the articles was by Nouriel Roubini. In the linked article below, he argues that slow economic growth may be the new global norm.

At the centre of the problem is a fall in the rate of potential economic growth. This has been caused by a lack of investment, which has slowed the pace of innovation and the growth in labour productivity.

The lack of investment, in turn, has been caused by a lack of spending by both households and governments. What is the point in investing in new capacity, argue firms, if they already have spare capacity?

Low consumer spending is partly the result of a redistribution of income from low- and middle-income households (who have a high marginal propensity to consume) to high-income households and corporations (who have a low mpc). Low spending is also the result of both consumers and governments attempting to reduce their levels of debt by cutting back spending.

Low growth leads to hysteresis – the process whereby low actual growth leads to low potential growth. The reason is that the unemployed become deskilled and the lack of investment by firms reduces the innovation that is necessary to embed new technologies.

Read Roubini’s analysis and consider the policy implications.


Has the global economic growth malaise become the ‘new normal’? The Guardian, Nouriel Roubini (2/5/16)


  1. Explain what is meant by ‘hysteresis’ and how the concept is relevant in explaining low global economic growth.
  2. Why has there been a reduction in the marginal propensity to consume in recent years? What is the implication of this for the multiplier and economic recovery?
  3. Explain what Roubini means by ‘a painful de-leveraging process’. What are the implications of this process?
  4. How important are structural reforms and what forms could these take? Why has there been a reluctance for governments to institute such reforms?
  5. ‘Asymmetric adjustment between debtor and creditor economies has also undermined growth.’ Explain what Roubini means by this.
  6. Why are governments reluctant to use fiscal policy to boost both actual and potential economic growth?
  7. What feasible policy measures could be taken to boost actual and potential economic growth?