2.1.2—Individual and market demand/supply

An individual demand curve shows one consumer’s quantities demanded at different prices; a market demand curve sums the quantities demanded by all consumers at each price. The same horizontal summation applies to supply.

Market curves depend on the number and characteristics of buyers or sellers. A change in the population or firms can change the market curve even if each individual curve is unchanged.

At £2, three consumers demand 2, 1 and 4 units, so market demand is 7 units at £2.

Do not add prices vertically for ordinary market demand and supply; add quantities at the same price.