Measuring economic activity and illustrating its variations

A model showing how money flows between households and firms in an economy. Households provide factors of production and receive income; firms produce goods/services and receive spending. Money flows in a continuous circle.

Output approach: sum of value added by all firms. Income approach: sum of all incomes earned (wages, profits, rent, interest). Expenditure approach: sum of all spending (C + I + G + X − M). All three should give the same result.

The total monetary value of all final goods and services produced within a country's borders in a given time period (usually one year). It is the most widely used measure of economic activity.

To avoid double counting. Intermediate goods (components/raw materials used to make other goods) are already included in the value of the final product. Counting them separately would inflate GDP.

GDP = C + I + G + (X − M), where C = consumer spending, I = investment (firms' capital spending), G = government spending, X = exports, M = imports. (X − M) is net exports.

Savings (S): income not spent on consumption. Taxation (T): income taken by the government. Imports (M): spending that leaves the domestic economy. All three reduce the flow of spending within the economy.

Investment (I): firms' spending on capital goods. Government spending (G): public expenditure on goods and services. Exports (X): foreign spending on domestic output. All three add to the flow of spending.

GDP measures output produced within a country's borders (by anyone). GNI (Gross National Income) measures income earned by a country's nationals, wherever they are in the world. GNI = GDP + net income from abroad.

Value added is the increase in value at each stage of production. It equals the selling price minus the cost of intermediate inputs. Summing value added across all firms avoids double counting.

GDP excludes: unpaid work (household, volunteering), the informal/shadow economy, environmental degradation, quality of life, income distribution, and leisure. It is a measure of quantity of output, not well-being.

Every dollar spent (expenditure) is a dollar earned by someone (income) for producing something (output). Spending = income = output is the fundamental identity of the circular flow of income.

When total injections equal total leakages: I + G + X = S + T + M. If injections > leakages, the economy expands (GDP rises). If leakages > injections, the economy contracts (GDP falls).

Consumer spending (C) is usually the largest component, often 50–70% of GDP. This is why consumer confidence and household income are so important for economic growth.

GDP is widely available, regularly updated, allows international comparisons, and correlates with many measures of living standards. No single alternative captures the breadth of information GDP provides, so it remains the standard benchmark.

More injections (e.g., increased government spending or investment) boost total spending in the economy, increasing output, employment, and income. Through the multiplier effect, the final increase in GDP may be larger than the initial injection.

GDP misses the informal economy (cash-in-hand work, unregistered businesses), household production (cooking, childcare, DIY), and volunteer work. In developing countries, the informal sector can be 30–60% of total activity.

GDP per capita = GDP ÷ population. It gives the average output or income per person, allowing fairer comparisons between countries of different sizes. A country can have high GDP but low GDP per capita if its population is very large.

Nominal GDP is measured at current prices (includes inflation). Real GDP is adjusted for inflation using a base year's prices. Real GDP gives a more accurate picture of actual output changes over time.

GDP counts output but not happiness, leisure, health, freedom, or environmental quality. A country could have high GDP but long working hours, polluted air, and poor mental health. GDP measures quantity, not quality, of economic life.

A method of adjusting GDP to account for differences in price levels between countries. PPP converts GDP using exchange rates that equalise the purchasing power of currencies, making international living standard comparisons more meaningful.

Nominal GDP can rise just because prices increased, even if actual output fell. Real GDP strips out price changes, showing whether the economy truly produced more goods and services. It is essential for meaningful comparisons over time.

Market exchange rates don't reflect the true cost of living. $1 buys much more in India than in Switzerland. PPP adjusts for these price differences, giving a more accurate picture of actual living standards in each country.

GDP can rise from "bads" — war spending, pollution clean-up, natural disaster rebuilding, and healthcare for preventable diseases all increase GDP. Growth driven by negative events does not indicate improved welfare.

Real GDP = Nominal GDP ÷ GDP deflator × 100. The GDP deflator is a price index that reflects the overall price level. Alternatively, real GDP can be calculated using constant (base year) prices for all goods and services.

HDI (Human Development Index), GNH (Gross National Happiness — Bhutan), Green GDP (adjusts for environmental damage), OECD Better Life Index. These capture health, education, environment, and subjective well-being that GDP misses.

A price index that measures the average price level of all goods and services included in GDP. It is broader than CPI (which only covers consumer goods). GDP deflator = (Nominal GDP ÷ Real GDP) × 100.

It is an average and hides income distribution. A country with very high inequality may have a high GDP per capita while most citizens are poor. It also doesn't capture unpaid work, environmental costs, or quality of life.

China and India move up significantly when measured in PPP terms because goods are much cheaper there. Luxembourg and Norway appear less dominant. PPP gives developing countries a fairer representation of their economic size.

Real GDP rose by approximately 2%. The 5% nominal increase includes 3% inflation and about 2% real growth. This shows why we must adjust for inflation to see the true change in output.

GDP counts resource extraction as income without deducting the depletion of natural capital. A country can boost GDP by cutting down forests or burning fossil fuels, but this destroys future productive capacity and well-being.

Changes in consumer confidence, investment spending, government policy (fiscal/monetary), and external shocks (global recession, export demand changes). These shift AD, causing output and employment to fluctuate.

The regular fluctuations in the level of economic activity (real GDP) over time. It consists of four phases: expansion (boom), peak, contraction (recession), and trough, repeating in an ongoing pattern around the long-run growth trend.

The difference between actual GDP and potential GDP. A positive (inflationary) gap means actual GDP exceeds potential. A negative (recessionary/deflationary) gap means actual GDP is below potential.

Rising real GDP, falling unemployment, increasing consumer and business confidence, rising investment, and potential inflationary pressure as the economy approaches or exceeds full capacity.

The economy operates beyond its sustainable capacity. Unemployment is below the natural rate, firms compete for scarce workers, wages rise, and demand-pull inflation accelerates. This is unsustainable in the long run.

Oil price shocks, technological changes, natural disasters, pandemics, and changes in input costs. These shift SRAS (short-run) or LRAS (long-run), affecting output and prices simultaneously.

Confidence is self-reinforcing. When consumers feel optimistic, they spend more → firms invest → jobs created → more confidence. When pessimistic, the reverse: spending falls → firms cut back → job losses → less confidence. This amplifies cycles.

Falling real GDP (technically, two consecutive quarters of negative growth), rising unemployment, declining consumer and business confidence, falling investment, and downward pressure on prices.

The economy operates below potential. There are unemployed resources (workers and machinery), low inflation or deflation, low confidence, and wasted productive capacity. The economy is in recession or sluggish growth.

The upward-sloping line that represents the economy's potential output over time. Actual GDP fluctuates around this trend. The trend rises due to improvements in technology, capital, labour force, and productivity.

Where AD intersects SRAS to the right of LRAS = inflationary gap (actual > potential). Where AD intersects SRAS to the left of LRAS = deflationary gap (actual < potential). At LRAS = no gap.

A global recession reduces demand for exports; an oil price spike raises costs; a financial crisis in trading partners reduces FDI and credit. Small, open economies are especially vulnerable to external shocks.

Negative gap: expansionary fiscal/monetary policy to boost AD. Positive gap: contractionary policy to reduce AD and cool inflation. Supply-side policies can shift LRAS right, closing both types of gap.

A technical recession is defined as two consecutive quarters of negative real GDP growth. This is a widely used benchmark but may not capture the full picture — employment, income, and consumer spending are also important indicators.

Inappropriate policy can destabilise: over-stimulating an economy near full capacity or cutting spending during recession. Good counter-cyclical policy (expansionary in downturns, contractionary in booms) can smooth the cycle.