Understanding Supply and Demand in IB Economics
In IB Economics, supply and demand are the foundation of microeconomics — explaining how prices and quantities of goods and services are determined in a market. These forces interact to create market equilibrium, where supply equals demand.
Mastering supply and demand is essential for Paper 1 essays and Paper 3 quantitative analysis. Every economic system, from free markets to mixed economies, depends on these principles to allocate scarce resources efficiently.
The Law of Demand | Consumer Behavior in IB Economics
The law of demand states that, ceteris paribus (all else equal), when the price of a good decreases, the quantity demanded increases — and when the price rises, demand falls.
Why Demand Slopes Downward
- Substitution effect: As prices fall, consumers switch from more expensive alternatives to the cheaper good.
- Income effect: A lower price increases consumers’ real purchasing power.
- Diminishing marginal utility: The additional satisfaction gained from consuming extra units declines, so consumers buy more only at lower prices.
Non-Price Determinants of Demand
Demand can shift due to factors other than price:
- Changes in income
- Consumer preferences and tastes
- Prices of substitutes or complements
- Population size and demographics
- Future expectations
A rightward shift means increased demand at all price levels, while a leftward shift means reduced demand.
