The meaning of markets and demand

Markets are places where buyers and sellers come together to trade goods or services. The price and amount of each good or service traded depend on the balance between demand and supply.

Key features of markets

• In a market, the interaction of demand and supply sets the price level and the quantity of goods or services exchanged.
• Diagrams are used to illustrate demand and supply levels, showing how price relates to the quantity demanded or supplied.

Demand

Demand refers to the amount of a good or service that buyers are willing and able to purchase at a specific price during a certain period.

Demand curves and movements along them

A demand curve illustrates how the quantity demanded changes with price. It shows, at any point, how much of a good or service would be bought at a particular price.

Characteristics of demand curves

• Demand curves typically slope downwards from left to right, meaning that as price rises, quantity demanded falls, and as price drops, quantity demanded increases.
• This downward slope occurs because buyers generally seek the lowest possible prices; lower prices attract more buyers who can afford the item.
• The relationship can also be linked to the law of diminishing marginal utility.
• Demand curves are often drawn as straight lines but can be curved; they are usually labelled 'D'.

Movements along the demand curve

Movements along the curve happen only due to price changes.

Types of movements:

• Extension in demand - A price decrease leads to higher quantity demanded, shown as a movement down and to the right along the curve.
• Contraction in demand - A price increase leads to lower quantity demanded, shown as a movement up and to the left along the curve.

For example, if the price falls from P_A to P_C, demand extends from Q_A to Q_C. If it rises from P_A to P_B, demand contracts from Q_A to Q_B.

Shifts in the demand curve

A shift in the demand curve occurs when the quantity demanded changes at every price level, not just due to price.

Types of shifts in demand

• Increase in demand - The curve shifts to the right (e.g., from D_Original to D_Right), meaning more is demanded at each price.
• Decrease in demand - The curve shifts to the left (e.g., from D_Original to D_Left), meaning less is demanded at each price.

Shifts are caused by factors other than the price of the good itself, unlike movements along the curve which are solely due to price changes.

Factors causing shifts in demand

Various influences can change demand at all price levels, leading to a shift in the curve.

Changes in tastes and fashion

• If a good becomes more popular, demand increases, shifting the curve to the right.
• If it falls out of fashion, demand decreases, shifting the curve to the left.

Changes in real income

Real income is the quantity of goods or services a person's earnings can buy. It affects demand differently depending on the type of good.

Impact on different types of goods:

• Normal goods - Items like electronic gadgets see higher demand when real income rises, shifting the curve to the right.
• Inferior goods - Items like budget clothing see lower demand when real income increases, shifting the curve to the left.

Income distribution

A more equal spread of income (less gap between rich and poor) can reduce demand for luxury items (shift left) while increasing demand for everyday goods (shift right).

How demand changes in interrelated markets

Markets are often connected, so changes in one can influence demand in another through different relationships.

Types of interrelated demand

• Substitute goods (competitive demand) - Alternatives like tea and coffee. If the price of tea rises, demand for tea falls and demand for coffee increases, shifting coffee's demand curve to the right.
• Complementary goods (joint demand) - Items used together, such as printers and ink cartridges. A price increase in printers reduces demand for printers and also for ink, shifting the ink demand curve to the left.
• New products - Launching a new item can decrease demand for substitutes (shift left) and increase demand for complements (shift right).
• Derived demand - Demand for something needed to produce another good, like steel for cars. Higher car demand increases derived demand for steel, shifting its curve to the right.
• Composite demand - When a good has multiple uses, like wheat for bread or animal feed. Increased demand for bread can reduce supply for feed, potentially shifting the feed supply curve left and affecting prices.