GCSE Economics: How Markets Work — Revision Notes

Condensed for the final weeks. For the full explanation, use the How Markets Work study guide.

The economic problem

Scarcity — unlimited wants, limited resources. So choices are made, and every choice has an opportunity cost: the next best alternative given up.

The four factors of production and their rewards: land–rent, labour–wages, capital–interest, enterprise–profit. Capital is machinery and equipment, not money.

Demand and supply

Demand slopes downward; supply slopes upward.

The distinction that decides most marks:

A change in the good’s own price causes a movement along the curve. A change in anything else causes a shift of the whole curve.

Conditions of demand: income, price of substitutes, price of complements, tastes and fashion, population, advertising, expectations.

Conditions of supply: production costs, technology, taxes, subsidies, number of firms, weather.

Note that for an inferior good, demand falls as income rises.

Equilibrium

Where demand meets supply.

• Price above equilibrium → excess supply (surplus) → price falls.
• Price below equilibrium → excess demand (shortage) → price rises.

Answering “explain the effect of X on the market” needs four steps: which curve shifts, in which direction, the new equilibrium, and the effect on both price and quantity. Answering only about price gives away half the marks.

The price mechanism performs three jobs at once: it signals to producers where resources are wanted, it incentivises them to supply more of what is scarce and profitable, and it rations a limited quantity of goods among the buyers willing to pay the going price. All three follow directly from the same self-correcting movement towards equilibrium described above.

Elasticity

PED = %change in quantity demanded / %change in price

PED	Meaning	Raising price will
Greater than 1 — elastic	Very responsive	Reduce revenue
Less than 1 — inelastic	Barely responds	Increase revenue

Determinants: availability of substitutes (the most important), necessity or luxury, proportion of income spent, whether it is addictive, and time.

This explains why taxes on tobacco and fuel raise so much revenue: demand is inelastic, so consumption barely falls and consumers bear most of the tax. It also explains why such taxes work poorly as behaviour-change tools — the same fact from the other side.

Worked example. Bad weather destroys a third of the coffee harvest — analyse the effect on the coffee market.

Supply shifts LEFT (less available at every price); demand is unchanged.
At the old price -> excess demand (a shortage) -> price is bid UP -> quantity traded FALLS.

Coffee has few close substitutes, so demand is relatively inelastic:
the price rise is large, the fall in quantity comparatively small,
so total revenue to the remaining growers may actually RISE.

The analysis mark is that last line — most candidates stop at “the price rises” and never link it back to elasticity and revenue.

Production and costs

total cost = fixed costs + variable costs
profit     = total revenue - total costs

Fixed costs do not change with output — rent, insurance, salaries. Variable costs do — raw materials, hourly wages.

Economies of scale reduce average cost as a firm grows: purchasing, technical, financial, marketing, managerial. Note the word average — total costs still rise with output; it is cost per unit that falls.

Diseconomies of scale raise average cost when a firm becomes too large: poor communication, weak coordination, falling motivation.

Competition

Market	Firms	Effect
Competitive	Many	Lower prices, more choice, better quality, more innovation
Monopoly	One dominant	Higher prices, less choice, but possible economies of scale and R&D funding

Competition benefits consumers through price, choice and quality. Monopoly is not automatically bad — the balanced answer weighs higher prices against lower unit costs from economies of scale.

Market failure

Failure	Consequence
Negative externality	Third parties bear costs — over-production
Positive externality	Third parties gain benefits — under-production
Public goods	Non-excludable and non-rival — free riding means the market provides none
Merit goods	Under-consumed because benefits are underestimated
Demerit goods	Over-consumed because harms are underestimated

A public good needs both properties. Street lighting and national defence qualify; healthcare and education are merit goods, since they can be and are sold privately.

Government intervention: indirect taxes, subsidies, regulation, state provision, minimum and maximum prices, information campaigns.

• A maximum price below equilibrium creates shortages, queues and black markets.
• A minimum price above equilibrium creates a surplus.

Both only have an effect on the correct side of equilibrium — a maximum price set above equilibrium changes nothing.

Exam traps

• Treating a price change as a shift of the demand curve.
• Calling money a factor of production.
• Answering about price only when quantity is also required.
• Giving one property of a public good.
• Confusing merit goods with public goods.
• Saying economies of scale cut total costs.
• Drawing a price control on the wrong side of equilibrium.

Self-test

1. Define opportunity cost.
2. What causes a movement along the demand curve, and what causes a shift?
3. If PED = 0.3, what happens to revenue when price rises, and why?
4. Give both properties of a public good.
5. What happens when a maximum price is set below equilibrium?

Answers: 1. The next best alternative forgone when a choice is made. 2. A change in the good’s own price causes a movement along; a change in any other condition of demand causes a shift. 3. Revenue rises — demand is inelastic, so quantity falls proportionally less than the price increases. 4. Non-excludable and non-rival. 5. Quantity demanded exceeds quantity supplied, creating a shortage — with queues and potentially a black market.