AQA GCSE Economics: Market structures, monopoly and oligopoly (8136)

This guide covers sections 3.1.5.1 to 3.1.5.3 of the AQA specification for GCSE Economics (8136), first taught from September 2017: the range of market structures, competitive markets and non-competitive markets, including monopoly and oligopoly. The specification has no tiers, so everything here is common content. Section 3.1.5.4, the labour market, is a separate topic and is not covered here. All firms, towns and figures below are invented for practice.

Use it with the revision notes and the practice questions. The wider How Markets Work guide, the AQA GCSE Economics hub and the checklist sit alongside it. To find your weak spots first, try the free diagnostics.

What you need to be able to do

Section	You must be able to
3.1.5.1	Explain that there is a range of market structures, and distinguish them by number of producers, degree of product differentiation and ease of entry
3.1.5.2	Explain what a competitive market is, how producers operate in one, and its impact on price, choice, consumers, producers and workers; explain why profits are likely to be lower than in a market dominated by a few producers
3.1.5.3	Explain what a non-competitive market is and how producers operate in one; its impact on price and choice; the meaning of monopoly and oligopoly; the causes and consequences of monopolistic and oligopolistic power

3.1.5.1 A range of market structures

A market structure is the set of features that shape how firms in a market behave: how many producers there are, how alike their products are and how easily a new firm can join. There is a range. At one end are markets with many small producers. At the other is a market with a single producer. Most real markets sit somewhere between.

Three factors are used to tell structures apart.

Factor	Competitive end	Non-competitive end
Number of producers	Many	One or a few
Product differentiation	Products are similar, or buyers see little difference	Products are different, branded or unique
Ease of entry	Easy and cheap to start up	Hard: high costs or other barriers

Product differentiation means making your product different from rivals’, through branding, design, quality or service, so that buyers prefer it. Ease of entry means how easily new firms can set up and sell in the market.

Think of an invented town, Dunmere. It has 40 window cleaners, each with a ladder and a van. It also has one rail operator and three supermarket chains. The three markets have very different structures.

Worked example: market shares

A firm’s market share is its slice of the total sales made by all firms in the market, written as a percentage. In an invented regional broadband market, five firms have these shares.

Firm	A	B	C	D	E	Total
Share (%)	38	27	15	12	8	100

The two largest firms together hold 38 + 27 = 65%. The three largest hold 38 + 27 + 15 = 80%. When a few producers hold most of the market, it is said to be concentrated or dominated by a small number of producers. Compare the window cleaners: with 40 firms of equal size, each holds 100 ÷ 40 = 2.5%. No single cleaner can dominate.

3.1.5.2 Competitive markets

Meaning and characteristics

A competitive market is one where lots of sellers chase the same buyers. It is recognised by:

• a large number of producers, none big enough to control the price
• similar products, or only small differences between them
• easy entry and exit, so new firms can join and unprofitable firms can leave
• buyers who can easily compare prices and switch.

How producers operate

A firm in a competitive market has little power over price. If it charges more than rivals, customers go elsewhere. So it tends to:

• keep prices close to those of rivals
• keep costs low so that it can still make a profit
• compete on non-price factors: quality, service, speed, reliability, location and advertising
• respond quickly to what customers want.

Impact on price and choice

Competition pushes prices down and keeps them low, because a firm that overcharges loses sales. It gives consumers wide choice, because many firms offer many versions of the product. Firms also try to improve quality and service to win custom.

Impact on consumers, producers and workers

• Consumers gain from lower prices, more choice, better quality and better service. Because it is easy to switch, firms must keep their customers happy.
• Producers face pressure. Profit margins are squeezed, they must keep costs down and innovate, and weaker firms may be forced out. Efficient firms survive and may grow.
• Workers have mixed effects. Many firms competing for staff can mean more job opportunities and better chances of pay rises. But firms under price pressure may hold down pay, cut hours or close, which can make jobs less secure.

Why profits are likely to be lower

Profit is revenue minus total costs. In a competitive market:

1. firms cannot raise prices without losing customers, so revenue per unit is limited
2. rivals keep prices close to cost
3. if profits are high, new firms enter (entry is easy), increasing supply and pushing the price down
4. each firm has a small share of sales, so total profit per firm is small.

Where a few producers dominate, newcomers are kept out, so large profits can persist.

Worked example: profit in two markets

In Dunmere (invented figures), a window cleaner’s cost is £10.50 per clean. To keep the comparison simple, assume the dominant firm in the second market has the same cost.

	Competitive (many cleaners)	Dominated (three firms)
Price per clean	£12	£18
Cleans per week	60	600
Revenue	12 × 60 = £720	18 × 600 = £10,800
Total cost	10.50 × 60 = £630	10.50 × 600 = £6,300
Profit	720 − 630 = £90	10,800 − 6,300 = £4,500
Profit margin (profit ÷ revenue)	90 ÷ 720 = 12.5%	4,500 ÷ 10,800 = 41.7%

The dominant firm earns 50 times the profit and a margin over three times higher. Because costs per clean are equal, the whole margin gap comes from the higher price. This is an invented simplification: dominant firms may have lower costs through economies of scale.

3.1.5.3 Non-competitive markets

Meaning and characteristics

A non-competitive market is one where competition is limited because one firm or a few firms dominate. Its characteristics:

• one producer or a small number of large producers
• high barriers to entry, so new firms struggle to join
• products that may be highly differentiated or branded
• firms with some power to set prices rather than just accept them.

How producers operate

Producers in a non-competitive market can often set their own prices and keep profits high. They may spend on advertising and branding instead of cutting price. They may also hold back from competing fiercely.

Impact on price and choice

Compared with a competitive market, prices tend to be higher and choice narrower, since buyers can turn to fewer alternatives. In some cases there may be no alternative at all.

Monopoly

A monopoly exists where a single producer supplies the whole market. In everyday use, the word is also applied to a firm with a very large share of the market, which is better described as having monopolistic power. A monopolist has no direct rival.

Worked example: a monopoly price rise

The only operator of a mountain railway (invented) raises the adult fare from £20 to £26.

• Increase = 26 − 20 = £6
• Percentage rise = 6 ÷ 20 × 100 = 30%

Riders have no alternative route, so many keep paying. If a rival coach route led the railway to cut its fare to £22, the fall from £26 would be 4 ÷ 26 × 100 = 15.4%, leaving the fare 10% above the original £20.

Oligopoly

An oligopoly is a market where a handful of big sellers share most of the sales. The firms are interdependent: each one’s choices depend on how rivals are likely to respond. Cutting prices may start a price war. So oligopolists often avoid price competition and compete through branding, advertising, loyalty schemes and product features. They may also collude, though collusion is generally unlawful.

Worked example: interdependence

Two firms, X and Y, set a high or a low price. The table shows monthly profit in £000 as (X, Y). The figures are invented.

	Y high price	Y low price
X high price	(40, 40)	(15, 60)
X low price	(60, 15)	(25, 25)

If both keep the high price, each earns 40. If X cuts while Y holds, X gains 20 (from 40 to 60) and Y drops to 15. But Y is likely to respond, and if both cut, each earns only 25. Both cutting leaves total profit of 50, against 80 when both hold. This is why oligopolists fear price wars.

Causes of monopolistic and oligopolistic power

• Barriers to entry. High start-up costs, such as buildings or equipment, make entry hard. Established firms may also cut price to push out newcomers.
• Economies of scale. Large firms have lower unit costs than small ones, so newcomers cannot match their prices.
• Legal protection. Patents, copyrights and licences give a single firm sole rights for a period.
• Brand loyalty. Strong brands make customers reluctant to switch.
• Control of resources or outlets. Owning key supplies or distribution blocks rivals.
• Mergers and takeovers. Firms combine, reducing the number of producers.
• Natural growth. Successful firms win share until they dominate.

Consequences of monopolistic and oligopolistic power

For	Possible disadvantages	Possible advantages
Consumers	Higher prices, less choice, poorer service	Lower prices if economies of scale are passed on; better products funded by profit
Producers	Less pressure to cut costs or innovate (the dominant firm may become inefficient); smaller rivals squeezed out	High profits, which may be reinvested in research
Workers	Fewer employers to choose between	Large firms may offer job security and training

Worked example: do economies of scale justify size?

A manufacturer (invented) has a unit cost of £6 at 10,000 units and £4.50 at 40,000 units. The market price is £5.20.

• Small output: 5.20 − 6.00 = −£0.80 per unit, a loss.
• Large output: 5.20 − 4.50 = £0.70 per unit, so 0.70 × 40,000 = £28,000 profit.

Only the large firm can survive at that price, which helps explain how scale creates dominance. It could pass some saving on, but without competition it may not.

Evaluation: using the chains of reasoning

Strong answers build chains. For example: high start-up costs → few new entrants → existing firms face less rivalry → they can charge more without losing much trade → buyers pay more and have fewer options.

Then judge. The outcome depends on:

• how high the barriers really are
• whether the firm uses its power or fears new entrants
• whether lower costs are passed on to consumers
• whether the market is regulated.

Common errors

• Claiming a sole supplier always sets a high price. Say it can, and give the reason.
• Thinking oligopolists do not compete. They often rival each other fiercely, through branding and quality more than price.
• Confusing a large firm with a monopoly. A large firm in a competitive market is not a monopoly.
• Forgetting the three distinguishing factors when asked how structures differ.

Official syllabus

Source: AQA, GCSE Economics (8136) specification, for first teaching from September 2017, sections 3.1.5.1 to 3.1.5.3.