Final answer:
A demand curve can shift due to changes in income, tastes and preferences, population composition, and prices of related goods. An increase in demand shifts the curve rightward, while a decrease shifts it leftward. Factors like higher income generally increase demand, except for inferior goods, which see a decrease in demand as income rises.
Step-by-step explanation:
The demand curve can shift to the right (increase in demand) or left (decrease in demand) for various reasons. When people have higher incomes, they generally buy more of most goods. As incomes rise, consumers often buy more name brand groceries and new cars, and are more likely to own a home instead of renting. In contrast, an inferior good has a demand that falls as income rises, such as used cars or generic brand groceries, causing the demand curve for these products to shift to the left.
Other factors that can cause shifts in the demand curve include changes in tastes and preferences, such as the increased consumption of chicken over beef in the US, which leads to a rightward shift in the demand curve for chicken. The composition of the population also plays a role; an aging population may increase the demand for products like hearing aids. Lastly, the prices of related goods, especially substitutes and complements, can cause demand shifts. For instance, a decrease in the price of tablets may reduce the demand for laptops, shifting the demand curve for laptops to the left.