An economy growing at 1% a year doubles its output in seventy years, roughly a working lifetime. One growing at 7% doubles it in ten. Two countries starting level, separated by six percentage points of growth, will be unrecognisably different within a generation, and that gap is the single largest fact in economic history. Almost everything governments do to the macroeconomy is an attempt to move that number, which is why understanding what actually causes growth matters more than any other topic on the syllabus.
Economic growth
An increase in the real output of an economy over time, usually measured as the percentage change in real gross domestic product.
The word real is the mark. If output is measured at current prices, a figure can rise purely because prices rose while the same quantity of goods was produced. Real GDP strips inflation out, so a rise in real GDP means more goods and services, not dearer ones. A definition without 'real' is routinely marked down.
Approximate real GDP growth = nominal GDP growth - rate of inflationThe exact form is (1 + nominal growth) / (1 + inflation) - 1, which matters only when the rates are large. Cambridge accepts the subtraction. Formulae are not printed in any 9708 paper, so recall it.
Separating real growth from inflation
A country reports that its GDP measured at current prices rose by 7% last year. Inflation over the same period was 4%. Calculate the approximate real growth rate. Then state what would have happened to real output if inflation had been 9% instead.
What causes growth
Growth comes either from having more factors of production or from using them better. More labour comes from a rising population, higher participation or immigration. More capital comes from investment, meaning spending on machinery, buildings and infrastructure rather than on consumer goods. More land and raw materials may come from discovery or from bringing unused land into use. Using factors better means raising productivity, through education and training, better technology, improved management or increased specialisation. In the long run productivity matters most, because an economy cannot keep adding workers and machines forever but can keep getting better at using them.
Growth can also start from the demand side. When total demand in the economy rises, because consumers are more confident, the government spends more or exports rise, firms produce more to meet it, using workers and machines that were previously idle. That raises output as long as there are unused resources, but once they are all in use, extra demand raises prices rather than output, so lasting growth needs more or better resources.
Growth does not proceed smoothly. The business cycle describes the pattern economies follow around their long-run trend. In a boom, output is high and rising, unemployment is low and inflationary pressure builds. A downturn follows as demand weakens and growth slows. A recession, conventionally two consecutive quarters of falling real GDP, brings rising unemployment and falling confidence. Recovery then begins as demand returns and output rises back towards trend. The cycle is why an economy can have a strong long-run growth rate and still spend some years shrinking.
Recession
A period of falling real GDP, usually defined as two consecutive quarters of negative economic growth.
A recession can be caused by a fall in total demand, for example when consumers and firms lose confidence and cut spending, when interest rates rise sharply, or when a trading partner's economy slumps and buys fewer exports. It can also come from a fall in the quantity or quality of resources, such as a natural disaster, a war, a pandemic that keeps workers at home, or a sudden rise in the price of oil. The consequences spread widely. Consumers face lower incomes and job insecurity. Workers face unemployment and smaller pay rises. Firms see sales and profits fall and some close. The government collects less tax while paying out more in benefits, so its budget worsens.
Draw a diagram with real GDP on the vertical axis and time on the horizontal axis. Draw a straight upward-sloping trend line, then draw the actual path of GDP as a wave oscillating around it. Label boom, downturn, recession and recovery, and mark where unemployment would be highest and where inflationary pressure would be greatest.
Two things to get right. The trend line slopes upward, because long-run growth continues through the cycle; drawing it flat implies an economy that never grows. And the actual path crosses the trend line rather than merely touching it, since an economy in a boom is producing above its sustainable level, which is precisely why booms end.
Growth is desirable but not costless, and questions almost always want both sides. It raises average incomes and material living standards, creates jobs, and increases tax revenue so a government can fund healthcare and education without raising rates. Against that, growth can generate pollution and deplete non-renewable resources, and the benefits may go disproportionately to those who already have most, so inequality can widen even as the average rises. Rapid growth can also be inflationary, and producing more capital goods now means fewer consumer goods today. Whether growth is worth having is rarely the question; how it is achieved and who receives it usually is.
Governments promote growth in several ways. Fiscal and monetary policy can raise total demand in a recession, using spare capacity. Supply-side policies raise the quantity and quality of resources over the long run: spending on education and training, investment in infrastructure such as roads, energy and internet connections, lower taxes on firms to encourage investment, and support for research and new technology. Demand policies work quickly but only while resources are idle; supply-side policies are slower but raise what the economy can produce, so they are the route to growth that lasts.
A country's GDP at current prices rises by 5% while inflation is 8%. What has happened to real GDP?
Which of the following would raise an economy's long-run growth rate rather than simply its current output?
Actual and potential growth
At AS the essential distinction is between actual and potential growth, and almost every question depends on it. Actual growth is the change in real GDP actually recorded, which can come from using existing spare capacity more fully. Potential growth is the increase in what the economy is capable of producing, which requires more or better factors of production. An economy recovering from recession can post strong actual growth while its potential is unchanged, because it is simply putting idle resources back to work. Once it reaches capacity, further actual growth requires potential growth, and demand-side policy can no longer deliver it.
Output gap
The difference between the actual level of real GDP and the potential level the economy could produce with all its resources fully employed. A negative output gap means actual output is below potential; a positive gap means it is temporarily above it.
The business cycle has several causes, and they often combine. Changes in aggregate demand are the most common: swings in consumer and business confidence, which make spending on durable goods and investment volatile; changes in interest rates and credit conditions; and changes in the growth of trading partners, which move export demand. Investment is especially volatile because of the accelerator, since a change in the growth of demand causes a larger change in investment. Supply-side shocks, such as a sharp rise in the price of oil or a harvest failure, can cause a downturn directly. Government policy can make the cycle worse if stimulus or tightening arrives at the wrong time, and financial crises, when banks cut lending, can turn a slowdown into a deep recession.
Draw a production possibility curve with a point inside it. Show actual growth as a movement from that point towards the curve, and potential growth as an outward shift of the curve itself. Then draw an AD/AS diagram showing the same two things: an AD shift along a flat AS, and a rightward shift of LRAS.
Drawing both pairs is the point, because the same distinction appears in two diagrams and questions use either. On the PPC, actual growth uses capacity and potential growth creates it. On AD/AS, an AD shift raises output only while spare capacity exists, whereas an LRAS shift raises the sustainable level itself.
How investment delivers both kinds of growth
- Firms increase investment in new machinery and buildings, perhaps following a fall in interest rates or a cut in corporation tax.
- Investment is a component of aggregate demand, so AD shifts right immediately and actual output rises.
- The multiplier amplifies this, since the firms supplying the machinery gain income and spend part of it.
- Over the following years the new capital comes into use, so the capital stock per worker rises.
- Workers with more and better equipment produce more per hour, so labour productivity rises.
- Productive capacity increases, so LRAS shifts right and potential output grows.
- The economy can now sustain a higher level of output without generating inflation, so growth is non-inflationary rather than merely cyclical.
Investment is the one variable that appears on both sides of the model, raising demand now and supply later, and saying so explicitly is worth marks. It is also why investment is the component of AD that policy most often tries to protect during a downturn.
Practise this chain →The determinants of potential growth are worth listing precisely, because questions often ask why two countries with similar resources grow at different rates. Investment raises the capital stock, but only if it exceeds depreciation, since some investment merely replaces worn-out equipment. The size and quality of the labour force matter, through demographics, participation, migration, and above all education and health. Technological progress raises output from the same inputs and is the main driver of growth in advanced economies. Institutional quality matters too: secure property rights, enforceable contracts and low corruption determine whether investment happens at all, which is why the same capital produces very different results in different countries.
An economy recovering from a deep recession records 4% real GDP growth. Which is the most likely explanation?
Applied context
China's growth from the late 1970s onwards is the largest episode of sustained growth on record and is instructive precisely because it changed character. The early decades were driven by factor accumulation: moving vast numbers of workers from low-productivity agriculture into manufacturing, and investing an unusually high share of national income in capital. That model produced extraordinary rates but was always finite, since the pool of surplus rural labour eventually thins and additional capital yields progressively less. The subsequent slowdown and the shift in emphasis towards productivity, services and domestic consumption illustrates the general point that growth by accumulation runs into diminishing returns while growth by productivity improvement need not.
Use this to support the analytical claim that the source of growth determines whether it can be sustained, rather than as a narrative. It works equally well in development questions.