Change in Quantity Demanded

It indicates the change in the specific amount of the goods; the buyer may be willing or able to buy. It shows the change from one price-quantity pair to another, caused by the change in demand price, and can be illustrated by the movement along the commodity demand curve.  

The only variable that can result in a transformation in quantity demanded is the price and all the other factors cause a change in the demand, where the determinants are the buyer’s income, the preference/tastes, investing in the future/ expectations, price, and market size value.

These determinants keep altering and the amendments can cause the curves to shift, even as, a shortage or surplus can cause imbalance where the market may remain in a temporary state of disequilibrium.

The shortage and surplus cause the price of the goods to change and the price modifications can result in a change in quantity demanded (or supplied), which eliminates the shortage or surplus and restores the market equilibrium. 

This can be explained by the example – where the consumer may buy more movie tickets if the rate is reduced from $10 to $5.

Similarly, customers may spend more on luxury goods, or eat out more, if the expense of such luxuries is less due to discounts offers or other factors; however, they may immediately stop buying luxury goods or eating out if the prices are very high.  

There are certain conditions like indirect demands where the need for one item depends on others like the markets for car and steel are interconnected. 

Sometimes the demand is elastic where the revenues will decrease following an increase in the price of the product and the added revenues generated per unit sold may be less than the revenues lost from the drop in the quantity.

On the other hand, revenues can increase following an increase in the price of the product; if it has an inelastic market since the added revenues generated through the sales will be higher than the amount lost from diminished sales.