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Economic growth — the increase in an economy's output over time — is perhaps the most important macroeconomic objective. It determines living standards, employment opportunities, and a country's global influence. This lesson examines the distinction between actual and potential growth, the key models of economic growth, and the factors that drive long-run prosperity.
Key Definition: Actual growth is the annual percentage increase in real GDP — the rate at which the economy's output actually expands.
Key Definition: Potential growth is the increase in the economy's productive capacity over time — the rate at which potential GDP (the maximum output the economy can sustain without generating inflationary pressure) increases.
| Concept | Shown On Diagram | Caused By |
|---|---|---|
| Actual growth | Movement of equilibrium output towards (or beyond) the PPF, or a rightward movement along the LRAS curve | Increase in aggregate demand (C, I, G, X−M); recovery from recession; improved capacity utilisation |
| Potential growth | Outward shift of the Production Possibility Frontier (PPF) or rightward shift of the LRAS curve | Increase in quantity or quality of factors of production (land, labour, capital, enterprise) |
An economy can experience actual growth (using up spare capacity) without potential growth if it is recovering from a recession and closing a negative output gap. Conversely, potential growth can occur (the PPF shifts outward) even if actual growth is zero because the economy is in recession and not utilising its increased capacity.
Exam Tip: This distinction is frequently tested. To achieve the highest marks, explain that actual growth can occur by moving towards the PPF (using spare capacity), while potential growth requires the PPF itself to shift outward. Use a diagram to illustrate both.
Investment in physical capital — machinery, factories, infrastructure, technology — increases the stock of capital available for production. Higher capital per worker (capital deepening) raises labour productivity and output.
Gross investment must exceed depreciation (the wearing out of existing capital) for the capital stock to grow. Net investment = Gross investment − Depreciation.
UK gross fixed capital formation was approximately 17% of GDP in 2023, below the OECD average of around 21%. Many economists argue that the UK's relatively low investment rate is a key explanation for its productivity puzzle.
An increase in the size of the labour force (through population growth, immigration, or higher participation rates) increases the economy's capacity to produce. However, what matters more for GDP per capita is the quality of the labour force.
Key Definition: Human capital is the stock of knowledge, skills, experience, and health embodied in the workforce. Investment in education, training, and healthcare increases human capital.
Gary Becker (1964) pioneered the economic analysis of human capital, showing that education and training yield returns analogous to investment in physical capital. Countries with higher levels of human capital tend to have higher productivity and GDP per capita.
UK context: The expansion of higher education (participation rose from 15% in the 1980s to over 50% by 2020) has significantly increased the UK's human capital stock, though concerns remain about skills gaps in STEM subjects and vocational training.
Technological innovation is widely regarded as the most important driver of long-run growth. New technologies — from the spinning jenny (1764) to artificial intelligence (2020s) — increase productivity by enabling more output from the same inputs.
Robert Solow (1957) estimated that approximately 87.5% of US economic growth between 1909 and 1949 was attributable to technological progress (the Solow residual), with only the remainder explained by increases in capital and labour. This finding had a transformative effect on growth theory.
Douglass North (1990) and Daron Acemoglu, Simon Johnson, and James Robinson (2001, 2012) emphasised the role of institutions — property rights, the rule of law, contract enforcement, stable governance, low corruption — in determining long-run growth. Countries with inclusive institutions (that protect property rights, encourage competition, and provide public goods) tend to grow faster than those with extractive institutions (that concentrate power and wealth in the hands of a few).
Countries with abundant natural resources (oil, minerals, fertile land) have a potential source of growth, but this is neither necessary nor sufficient. Japan and Singapore achieved remarkable growth with few natural resources, while many resource-rich countries suffer from the resource curse — the paradox that countries with abundant resources often have slower growth, more corruption, and more conflict (first identified by Richard Auty 1993, developed by Jeffrey Sachs and Andrew Warner 1995).
Roy Harrod (1939) and Evsey Domar (1946) independently developed a growth model focused on the role of savings and investment:
G = s / k
Where:
Implications:
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