What Is a Change in Demand and What Factors Affect It?

Demand in economics refers to the quantity of a good or service that consumers are willing and able to purchase at various price points within a specific time frame. This concept includes both the desire for a product and the financial capacity to acquire it. Demand constantly evolves, and understanding these shifts is important for businesses and consumers alike.

Understanding a Shift in Demand

A “change in demand,” or “shift in demand,” means consumers are willing and able to buy a different quantity of a good or service at every possible price. This alters the entire relationship between price and quantity demanded. For instance, if a new health trend emerges, people might demand more fresh produce at all price levels.

This is distinct from a “change in quantity demanded,” which is a movement along an existing demand curve. A change in quantity demanded occurs only when the product’s own price changes. For example, if a store lowers the price of soda, consumers might buy more, but this is a change in quantity demanded, not a shift in demand. A shift in demand is caused by non-price factors, moving the entire demand curve right (increase) or left (decrease).

Key Determinants of Demand Shifts

Several non-price factors can cause the entire demand curve to shift, reflecting changes in consumer behavior.

Consumer Income

For most “normal goods,” demand increases as consumer income rises, as individuals have more purchasing power. For example, a household whose income increases due to a new job may increase its demand for dining out at restaurants. Conversely, for “inferior goods,” demand tends to decrease as income rises because consumers can afford higher-quality alternatives. For instance, if a person’s income significantly increases, they might switch from using public transportation to purchasing a personal vehicle.

Tastes and Preferences

Trends, advertising campaigns, and evolving perceptions can alter what consumers desire. If a popular celebrity endorses a particular brand of athletic wear, the demand for that brand could increase across all price points.

Prices of Related Goods

This includes substitute goods and complementary goods. Substitute goods are those that can be used in place of another; if the price of one substitute rises, the demand for the other substitute will increase. For example, if the price of ground beef increases, consumers might shift their purchases towards chicken. Complementary goods are typically consumed together; a decrease in the price of one often leads to an increase in demand for the other. For instance, if the price of coffee makers drops, the demand for coffee beans might increase.

Consumer Expectations

Expectations about future conditions can also impact current demand. If consumers anticipate that the price of a certain electronic device will fall, they might delay their purchase, leading to a decrease in current demand. Similarly, expectations of a future income increase could lead to an immediate increase in demand for certain goods.

Number of Buyers

An increase in the total number of buyers in the market, such as through population growth or immigration, generally leads to a higher demand for goods and services. For example, a growing number of young families in a region could increase the demand for childcare services and family-sized vehicles.

Visualizing Demand Shifts

A change in demand is depicted graphically through a shift of the entire demand curve. The vertical axis on a demand graph represents price, while the horizontal axis represents the quantity demanded. The demand curve typically slopes downward from left to right, illustrating the law of demand where a higher price generally leads to a lower quantity demanded.

An increase in demand is shown as a rightward shift of the entire demand curve, indicating that at every given price, consumers are willing and able to purchase a greater quantity. For example, if a new scientific study highlights the health benefits of a certain fruit, its demand curve would shift to the right. Conversely, a decrease in demand is a leftward shift, signifying that at every price point, a smaller quantity is demanded.