What determines the demand for a good

• →Demand for a good refers to the quantity that consumers are willing and able to purchase at a given price over a given time period.
• →Several non-price factors — known as the conditions of demand — can shift the entire demand curve to the right or left, independent of the good's own price.
• →One of the most significant determinants is consumer income. For normal goods, a rise in real income increases demand, shifting the demand curve rightward, as consumers have greater purchasing power.
• →This means that during periods of economic growth, industries such as new car manufacturing or foreign holidays typically experience rising demand this causes upward pressure on equilibrium prices.
• →The prices of related goods also play a central role: a fall in the price of a complementary good such as a reduction in petrol prices increases the demand for cars, since the two goods are consumed together.
• →Conversely, a rise in the price of a substitute, such as bus fares rising, increases the demand for private car travel.
• →Tastes and preferences, influenced by advertising, social trends, or health guidance, can likewise shift demand substantially, the sustained growth in demand for plant-based food products over the last decade illustrates this clearly.
• →Derived demand is a further consideration: the demand for a factor of production, such as steel, is derived from the demand for the final good it is used to produce, such as vehicles. Therefore, a fall in consumer demand for cars reduces the derived demand for steel and the workers who produce it.
• →It is worth noting, however, that the relative importance of each determinant varies significantly across different goods and markets. In the market for housing access to credit (mortgages) is likely to be the most significant factor whereas in the market for ice creams, the weather is likely to be the most significant factor.

• →The conditions of demand are distinct from a movement along the demand curve; they cause the entire curve to shift, and students must be precise about which direction and why.
• →Income effects differ by good type: for normal goods, demand rises with income, while for inferior goods — such as own-brand supermarket products — demand falls as income rises, reflecting consumers switching to more expensive alternatives.
• →Derived demand applies when a good or factor is wanted not for its own sake but because it contributes to the production of another good; understanding the link between final goods markets and factor markets is essential here.
• →Complements and substitutes have opposite effects on demand: an increase in the price of a complement reduces demand for the related good, whereas an increase in the price of a substitute raises it.
• →Expectations matter: if consumers anticipate future price rises, they may bring forward purchases, increasing current demand — a dynamic relevant to housing markets and fuel, among others.

This question assesses understanding of AQA spec point 4.1.3.1 — The determinants of the demand for goods and services. At higher tariffs, it requires students to go beyond listing factors and instead demonstrate precise causal reasoning: explaining the mechanism by which a change in a condition of demand shifts the curve, and applying this to specific market contexts. The inclusion of derived demand in some versions of the question extends the analysis into factor markets, testing whether students can link goods markets and the markets for the inputs used to produce them. Evaluation at the 15-mark level is expected to consider the relative significance of different determinants or to reflect on the assumptions underpinning the analysis.

Examined 3 times across AQA since 2022.

The concept has appeared across both multiple-choice and extended writing formats, with the highest tariff recorded at 15 marks.

• →Price Determination in a Competitive Market (Advanced) — directly relevant because shifts in the demand curve, caused by changes in the conditions of demand, alter the equilibrium price and quantity in a competitive market, connecting this topic to the broader supply and demand framework.