Economic theory contains many laws that pertain to the concept of supply and demand. These two basic components are a strong foundation of economic law and theory. For the demand factor, there are variables within the theory of demand. Demand and quantity demanded can be a confusing concept. The reason for this is partially because they sound so similar and when many people talk about demand, what they really mean is quantity demanded.
The demand segment of economics surrounds the concept of need. Needs are what people see as a requirement in their daily lives. The economic law of demand dictates, all other factors being equal, the more expensive a good, the less of that item people demand; it is this perceived demand that affects price. When the price of a specific good drops, all other things being equal, people will be more inclined to buy more of that item.
When demand of an item changes, this means the demand curve shifts. There are a few factors which may influence this such as a change in customer preferences, the price of complement or substitute goods, income, buyer population and expectations of price change. Any of these factors can impact the direction of the demand curve.
To understand quantity demanded it is helpful to understand elasticity. Elasticity is defined as the level of flexibility people have in purchasing an item. Some items are totally elastic and have substitutes. The higher number of substitutes available, the more elastic that item is. On the other hand, some items are inelastic meaning regardless of price, people will continue to buy because there are no viable substitutes for an item. The level of elasticity has a direct effect on demand and quantity demanded.
When economists refer to quantity demanded they are talking about the maximum quantity buyers want to buy at the specified price. While quantity demanded is directly related to laws of demand, it does not necessarily correlate with demand itself. What this essentially means is that when the price of something drops, people demand more of the item because it is priced attractively enough where they want to buy more, and the quantity of the item they normally buy increases. Consequently, when the price increases people demand less of the product because they aren’t willing to pay a higher price, or top dollar, for the same item.
When the quantity demand changes with respect to the cost of an item, this is referred to as the elasticity of demand. The demand curve itself doesn’t change, but the quantity demanded is affected.
Example of Demand vs. Quantity Demanded
Essentially, when prices are higher, people will demand less quantity. People need to eat in order to thrive, and this is an absolute factor that cannot be altered. Food is an inelastic purchase. However, the kinds of foods purchased can be pretty elastic because there are many substitutions of the kinds of food people can buy and the price will impact the choices people make.
Regardless of price people will buy food, and this demand will likely not change because nutrition in some shape or form is a requirement of the human body; it is inelastic. Grocery stores or places that sell food will stay in business. However, while people need to eat, they do not necessarily need to have oranges in order to do so. Sure the human body requires vitamin C, but people can easily find this in other forms. If the price of oranges goes sky high, people are going to be more inclined to find another source of vitamin C that is more affordable; this is known as a substitution.
As a result, the quantity of the number of oranges demanded will go down. While vitamin C is inelastic and in demand, the sources of obtaining it are very elastic. On the other hand, say a grocery store decides to hold a huge sale on oranges. This is going to affect the amount people want to buy and change the quantity demanded. Since oranges are more affordable, the quantity demanded will increase because the price of the product is much more appealing.
There are many factors of supply and demand that will impact both demand and quantity demanded. If you can remember that the demand curve is a pictorial graph of the relationship that exists between price and quantity demanded, this should help you differentiate between demand and quantity demanded. Demand is the overall consumer need of a product, while the quantity demanded is the actual number of the items desired.
Leigh has been writing on the web since 2007. She has a high interest in business, tech, higher education, and Washington D.C. and Northern Virginia travel, but loves to write about a variety of topics. In addition to writing on Writedge, she also runs a blog about the Washington DC Metro Area and a photography blog Photos by Leigh Goessl.