Economics,
one step at a time.

A positive statement is testable against evidence, whereas a normative statement contains a value judgement about what ought to happen. The common error is: Any statement containing a number is normative and every statement without a number is positive.

Watch for: Do not stop after the first effect of The economic problem. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Productive efficiency means producing at the lowest feasible average cost; allocative efficiency means producing the mix and quantity that best matches preferences, commonly where price equals marginal cost. Therefore, A firm can cut unit cost and become more productively efficient while a monopoly output remains allocatively inefficient because price exceeds marginal cost. Avoid this misconception: Productive efficiency and allocative efficiency are interchangeable because both simply mean earning maximum profit.

Watch for: Do not stop after the first effect of The allocation of resources. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Opportunity cost is the value of the next best alternative forgone when a choice is made, not the sum of every rejected option. The common error is: Opportunity cost is the cash paid for the chosen option even when a better alternative is forgone.

Watch for: Do not stop after the first effect of Opportunity cost. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Barter requires each trader to want what the other offers at the same time, which raises transaction costs and limits exchange. The common error is: Barter works more efficiently than money because every good provides a common unit of account.

Watch for: Do not stop after the first effect of Specialisation and trade. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A non-price determinant such as income, tastes, population or a related good's price shifts demand at every own-price level. The common error is: A fall in the product's own price shifts demand right rather than causing an extension along the curve.

Watch for: Do not stop after the first effect of Demand. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Ceteris paribus, a higher price normally causes an extension in quantity supplied and a lower price causes a contraction along the existing supply curve. The common error is: A higher price shifts the supply curve right because firms supply a larger quantity.

Watch for: Do not stop after the first effect of Supply. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. A price change redistributes surplus between buyers and sellers and changes traded quantity, so its total welfare effect depends on the cause and any market failure. Therefore, A demand increase raises equilibrium price and usually enlarges producer surplus, but the change in consumer surplus is ambiguous because price and quantity move in opposite welfare directions. Avoid this misconception: Any rise in market price must reduce total economic surplus because every consumer pays more.

Watch for: Do not stop after the first effect of Consumer and producer surplus. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A shock in one market can alter demand or supply in related markets through complementarity, substitution or shared inputs. The common error is: Related markets can interact only when the two goods are bought in the same transaction.

Watch for: Do not stop after the first effect of The interaction of markets. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

When demand is price elastic, price and total revenue move in opposite directions; when demand is inelastic, they move in the same direction. The common error is: A price increase always raises total revenue because revenue per unit is higher.

Watch for: Do not stop after the first effect of Elasticity. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A marginal value is the change in a total caused by one additional unit; for discrete data it is the difference between successive total values. The common error is: A marginal value is found by dividing the total value by every unit produced.

Watch for: Do not stop after the first effect of The concept of the margin. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

With a negative externality, marginal social cost exceeds marginal private cost by the marginal external cost imposed on third parties. The common error is: External cost is the whole cost to society, so it equals private cost plus social cost.

Watch for: Do not stop after the first effect of Market failure and externalities. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Moral hazard occurs when protection from consequences changes behaviour after an agreement because actions are imperfectly observable. The common error is: Moral hazard is the same as a consumer underestimating a good's private benefit before purchase.

Watch for: Do not stop after the first effect of Information failure. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A quasi-public good has public-good features but is partly excludable or becomes rival under congestion, so classification depends on technology and use. The common error is: A quasi-public good must be supplied half by government and half by private firms.

Watch for: Do not stop after the first effect of Public goods. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A buffer stock buys output when price is low and sells stocks when price is high, but requires finance, storage and sustainable intervention prices. The common error is: A buffer stock stabilises price without ever buying, storing or selling the product.

Watch for: Do not stop after the first effect of Government intervention. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. The principal-agent problem arises when owners and managers have different objectives and owners cannot perfectly monitor managers, especially where ownership and control are separated. Therefore, Managers of a widely owned public company may pursue revenue growth that raises status or bonuses instead of shareholder profit. Avoid this misconception: The principal-agent problem affects only sole traders because owner and manager are the same person.

Watch for: Do not stop after the first effect of Business objectives. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

In the short run, adding a variable factor to fixed factors eventually causes marginal product to fall, which tends to make marginal cost rise. The common error is: Diminishing returns means total output must immediately fall when one more worker is hired.

Watch for: Do not stop after the first effect of Costs and economies of scale. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Total revenue is price times quantity, average revenue is total revenue divided by quantity, and marginal revenue is the change in total revenue from one more unit. The common error is: Marginal revenue equals total revenue divided by the number of units sold.

Watch for: Do not stop after the first effect of Revenue and profit. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Perfect competition assumes many small firms, homogeneous products, perfect information, factor mobility and no significant barriers to entry or exit. The common error is: Perfect competition requires one dominant firm to set the price for all smaller firms.

Watch for: Do not stop after the first effect of Perfect competition. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. A profit-maximising monopoly selects output where rising MC equals MR and then charges the price on its downward-sloping average-revenue curve. Therefore, If price at that output exceeds average cost, the price-cost rectangle measures supernormal profit. Avoid this misconception: A monopoly maximises profit by setting price equal to marginal revenue at the largest possible output.

Watch for: Do not stop after the first effect of Monopoly. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A firm in monopolistic competition maximises profit where MC equals MR and may earn supernormal profit or a loss in the short run. The common error is: Product differentiation forces price to equal marginal cost in every short-run equilibrium.

Watch for: Do not stop after the first effect of Monopolistic competition. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Because each large firm's outcome depends on rivals' responses, oligopolists may use game-theoretic reasoning rather than treat competitors' actions as fixed. Therefore, A mobile network considering a price cut anticipates whether rivals will match it before forecasting subscriber gain. Avoid this misconception: Interdependence means each firm can ignore rivals because its market share is too small to matter.

Watch for: Do not stop after the first effect of Oligopoly. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Economies of scale, network effects, customer switching costs, capacity constraints and incumbent retaliation can make nominally open markets hard to enter. The common error is: Removing a legal barrier automatically makes every market perfectly contestable.

Watch for: Do not stop after the first effect of Contestable markets. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Labour demand shifts with output demand, productivity, the price of output, technology and the price or productivity of substitute and complementary factors. Therefore, Training that raises worker productivity can increase MRP and shift labour demand right if other relevant conditions are unchanged. Avoid this misconception: Only the wage rate can alter labour demand, so productivity changes cause movement along the same curve.

Watch for: Do not stop after the first effect of Demand for labour. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

At higher wages the income effect of a wage rise may exceed the substitution effect, causing an individual to choose more leisure and fewer working hours. The common error is: A backward-bending supply curve means employers demand less labour when wages rise.

Watch for: Do not stop after the first effect of Supply of labour. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Wage differentials can reflect productivity, qualifications, risk, unsocial hours, labour immobility, discrimination, monopsony power and differences in labour demand and supply. Therefore, A dangerous remote job may require a compensating wage differential even if formal qualifications are modest. Avoid this misconception: Every wage difference proves one worker is more productive than another.

Watch for: Do not stop after the first effect of The interaction of labour markets. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Investment, government spending and exports inject demand into the circular flow; saving, taxation and imports withdraw spending from it. The common error is: Imports are an injection because foreign products enter the domestic economy.

Watch for: Do not stop after the first effect of Circular flow of income. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Changes in disposable income, confidence, wealth, interest rates, fiscal policy, foreign income or exchange rates can alter AD at every price level. The common error is: Higher confidence changes only the price level and cannot affect planned expenditure.

Watch for: Do not stop after the first effect of Aggregate demand. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

LRAS represents productive capacity and depends on factor quantity, factor quality, technology and institutions rather than the current price level. The common error is: A temporary rise in consumer confidence permanently shifts LRAS right.

Watch for: Do not stop after the first effect of Aggregate supply. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A rise in AD usually raises real output and the price level in the short run, but the size of each change depends on spare capacity and supply responsiveness. The common error is: A rightward AD shift must raise real output by the same amount in every economy.

Watch for: Do not stop after the first effect of The interaction of aggregate demand and supply. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

The accelerator links induced investment to changes in the growth of demand or output, because firms adjust capital stock to expected output needs. The common error is: The accelerator says investment rises whenever the level of demand is positive.

Watch for: Do not stop after the first effect of The multiplier and the accelerator. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Real GDP growth measures change in total real output; real GDP per capita divides by population and can move differently when population changes. The common error is: Any rise in real GDP guarantees the average material living standard rises.

Watch for: Do not stop after the first effect of Economic growth. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Development often changes employment and output shares from primary toward secondary and tertiary activity, but sequence and benefits depend on productivity, institutions and inclusiveness. Therefore, Moving workers from subsistence agriculture into productive manufacturing can raise income, while premature deindustrialisation may limit learning effects. Avoid this misconception: A larger service-sector share proves every worker has a high and secure income.

Watch for: Do not stop after the first effect of Development. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

An unemployed person is without work, available for work and actively seeking it; economically inactive people are not employed and not currently in the labour force. The common error is: Everyone without a paid job is counted as unemployed.

Watch for: Do not stop after the first effect of Employment. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A real value adjusts a nominal value for price-level change; approximately, real interest equals nominal interest minus inflation when rates are modest. The common error is: A positive nominal wage increase always raises purchasing power.

Watch for: Do not stop after the first effect of Inflation. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

The current-account balance sums net trade in goods, net trade in services, net primary income and net secondary income, retaining surplus and deficit signs. The common error is: Only exports and imports of physical goods belong in the current account.

Watch for: Do not stop after the first effect of Balance of payments. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Developed economies can differ in productivity, demographics, policy institutions, trade exposure and resource endowment, so similar income levels do not imply identical macroeconomic performance. Therefore, An ageing economy may have slower labour-force growth than a peer even when investment rates are similar. Avoid this misconception: All developed economies share the same inflation, growth and unemployment path because their income levels are high.

Watch for: Do not stop after the first effect of Trends in macroeconomic indicators. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Inequality can arise from education, technology, inheritance, asset ownership, labour-market power, discrimination, household structure and tax-benefit policy. The common error is: Income inequality is caused only by differences in individual effort.

Watch for: Do not stop after the first effect of Income distribution and welfare. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. If expected inflation adjusts, unemployment returns toward its natural rate and the long-run Phillips curve is vertical, so persistently higher inflation does not permanently reduce unemployment. Therefore, An unanticipated demand expansion may temporarily lower unemployment, but wage and price expectations can later shift the short-run curve upward. Avoid this misconception: The long-run Phillips curve slopes downward because higher inflation permanently creates more jobs.

Watch for: Do not stop after the first effect of The Phillips Curve. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Automatic stabilisers change taxes and benefits with the cycle without a new decision, while discretionary fiscal policy deliberately alters rates or spending. Therefore, During recession, lower income-tax receipts and higher unemployment benefits support disposable income automatically. Avoid this misconception: Any rise in benefit spending is discretionary because parliament originally created the benefit system.

Watch for: Do not stop after the first effect of Fiscal policy. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A policy-rate change can affect consumption, saving, investment, asset prices, exchange rates and expectations, then AD and inflation with variable lags. The common error is: A higher policy rate raises investment because saving becomes more rewarding.

Watch for: Do not stop after the first effect of Monetary policy. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Training, mobility support, wage flexibility, childcare and benefit design can improve labour-market adjustment, but insecure work or weak bargaining power can create equity and productivity costs. Therefore, Retraining can reduce structural unemployment, whereas simply lowering benefits may not create skills or vacancies. Avoid this misconception: Labour flexibility means removing every employment protection so wages can fall without limit.

Watch for: Do not stop after the first effect of Supply-side policy. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Faster domestic growth can raise imports and worsen the current account, but export-led growth or improved competitiveness can raise output while strengthening it. The common error is: A growing economy must always have a current-account deficit.

Watch for: Do not stop after the first effect of Policy conflicts. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Developed and emerging economies can participate at different stages of global value chains; upgrading depends on skills, infrastructure, institutions and domestic linkages rather than income label alone. Therefore, An emerging economy assembling electronics may capture more value after developing design and component capability. Avoid this misconception: Manufactured exports prove that every input and all value added originate domestically.

Watch for: Do not stop after the first effect of International trade. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Depreciation makes domestic output cheaper in foreign currency and imports dearer in domestic currency, but effects on trade balance and inflation depend on elasticities, contracts, capacity and pass-through. Therefore, Export volume may respond slowly after depreciation because contracts are fixed, while imported-input costs rise sooner. Avoid this misconception: Depreciation must immediately improve the current account because every export price falls.

Watch for: Do not stop after the first effect of Exchange rates. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Globalisation is increasing cross-border integration of goods, services, capital, production, technology and information, enabled by policy and falling coordination costs. The common error is: Globalisation means only a rise in physical merchandise exports.

Watch for: Do not stop after the first effect of Globalisation. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. A tariff benefits protected producers and raises government revenue but reduces consumer surplus and creates production and consumption deadweight losses in the standard small-country model. Therefore, The higher domestic price expands inefficient domestic output and suppresses some mutually beneficial consumption. Avoid this misconception: A tariff's producer gain and government revenue always exceed the consumer loss.

Watch for: Do not stop after the first effect of Trade policies and negotiations. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Interest rates reflect demand and supply for loanable funds, liquidity preference and money supply, alongside central-bank policy and risk premiums; the relevant model must be stated. Therefore, Higher perceived default risk can widen a borrower's rate above the policy rate even if the central bank does not change policy. Avoid this misconception: One economy has a single interest rate applying identically to every borrower and maturity.

Watch for: Do not stop after the first effect of Money and interest rates. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

Financial institutions mobilise saving, assess and diversify risk, provide payments, transform maturities and allocate funds to investment. The common error is: Financial intermediation removes all risk because savers never face default or liquidity problems.

Watch for: Do not stop after the first effect of The financial sector. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.

A supported judgement states the economic mechanism and applies it to the context. Microprudential rules protect individual institutions, while macroprudential tools target system-wide cycles and interconnected risk through capital, liquidity or borrower-based limits. Therefore, A countercyclical capital buffer can require extra resilience during a credit boom and be released during stress. Avoid this misconception: Deposit insurance alone eliminates bank risk and removes the need for supervision.

Watch for: Do not stop after the first effect of Financial regulation. Build the chain of reasoning, use the context and explain what could weaken or reverse the outcome.