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supply and demand, in economics, relationship between the quantity of a commodity that producers wish to sell at various prices and the quantity that consumers wish to buy. It is the main model of price determination used in economic theory. The price of a commodity is determined by the interaction of supply and demand in a market. The resulting price is referred to as the equilibrium price and represents an agreement between producers and consumers of the good. In equilibrium the quantity of a good supplied by producers equals the quantity demanded by consumers. increase in demandEncyclopædia Britannica, Inc. The quantity of a commodity demanded depends on the price of that commodity and potentially on many other factors, such as the prices of other commodities, the incomes and preferences of consumers, and seasonal effects. In basic economic analysis, all factors except the price of the commodity are often held constant; the analysis then involves examining the relationship between various price levels and the maximum quantity that would potentially be purchased by consumers at each of those prices. The price-quantity combinations may be plotted on a curve, known as a demand curve, with price represented on the vertical axis and quantity represented on the horizontal axis. A demand curve is almost always downward-sloping, reflecting the willingness of consumers to purchase more of the commodity at lower price levels. Any change in non-price factors would cause a shift in the demand curve, whereas changes in the price of the commodity can be traced along a fixed demand curve.
decrease in supplyEncyclopædia Britannica, Inc.
The quantity of a commodity that is supplied in the market depends not only on the price obtainable for the commodity but also on potentially many other factors, such as the prices of substitute products, the production technology, and the availability and cost of labour and other factors of production. In basic economic analysis, analyzing supply involves looking at the relationship between various prices and the quantity potentially offered by producers at each price, again holding constant all other factors that could influence the price. Those price-quantity combinations may be plotted on a curve, known as a supply curve, with price represented on the vertical axis and quantity represented on the horizontal axis. A supply curve is usually upward-sloping, reflecting the willingness of producers to sell more of the commodity they produce in a market with higher prices. Any change in non-price factors would cause a shift in the supply curve, whereas changes in the price of the commodity can be traced along a fixed supply curve.
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The supply curve is a graphic representation of the correlation between the cost of a good or service and the quantity supplied for a given period. In a typical illustration, the price will appear on the left vertical axis, while the quantity supplied will appear on the horizontal axis.
- On most supply curves, as the price of a good increases, the quantity of goods supplied also increases.
- Supply curves can often show if a commodity will experience a price increase or decrease based on demand, and vice versa.
- The supply curve is shallower (closer to horizontal) for products with more elastic supply and steeper (closer to vertical) for products with less elastic supply.
- The supply curve, along with the demand curve, are the key components of the law of supply and demand.
The supply curve will move upward from left to right, which expresses the law of supply: As the price of a given commodity increases, the quantity supplied increases (all else being equal).
Note that this formulation implies that price is the independent variable, and quantity the dependent variable. In most disciplines, the independent variable appears on the horizontal or x-axis, but economics is an exception to this rule.
Image by Julie Bang © Investopedia 2019If a factor besides price or quantity changes, a new supply curve needs to be drawn. For example, say that some new soybean farmers enter the market, clearing forests and increasing the amount of land devoted to soybean cultivation. In this scenario, more soybeans will be produced even if the price remains the same, meaning that the supply curve itself shifts to the right (S2) in the graph below. In other words, supply will increase.
Technology is a leading cause of supply curve shifts.
Other factors can shift the supply curve as well, such as a change in the price of production. If a drought causes water prices to spike, the curve will shift to the left (S3). If the price of a substitute—from the supplier's perspective—such as corn increases, farmers will shift to growing that instead, and the supply of soybeans will decrease (S3).
If a new technology, such as a pest-resistant seed, increases yields, the supply curve will shift right (S2). If the future price of soybeans is higher than the current price, the supply will temporarily shift to the left (S3), since producers have an incentive to wait to sell.
Image by Julie Bang © Investopedia 2019Should the price of soybeans rise, farmers will have an incentive to plant less corn and more soybeans, and the total quantity of soybeans on the market will increase.
The degree to which rising prices translate into rising quantity is called supply elasticity or price elasticity of supply. If a 50% rise in soybean prices causes the number of soybeans produced to rise by 50%, the supply elasticity of soybeans is 1.
On the other hand, if a 50% rise in soybean prices only increases the quantity supplied by 10 percent, the supply elasticity is 0.2. The supply curve is shallower (closer to horizontal) for products with more elastic supply and steeper (closer to vertical) for products with less elastic supply.
The terminology surrounding supply can be confusing. "Quantity" or "quantity supplied" refers to the amount of the good or service, such as tons of soybeans, bushels of tomatoes, available hotel rooms, or hours of labor. In everyday usage, this might be called the "supply," but in economic theory, "supply" refers to the curve shown above, denoting the relationship between quantity supplied and price per unit.
Other factors can also cause changes in the supply curve, such as technology. Any advances that increase production and make it more efficient can cause a shift to the right in the supply curve. Similarly, market expectations and the number of sellers (or competition) can affect the curve as well.
The law of supply and demand is an economics concept whereby the price of a good will reach an equilibrium based on the amount of that good available (the supply) and the amount that customers want (the demand).
Supply and Demand Equillibrium.Image by Julie Bang © Investopedia 2020
The demand curve is the complement to the supply curve, in the law of supply and demand. Unlike the supply curve, the demand curve is downward-sloping, since the higher the price of a good, the less demand there will be for it, all else equal.
The supply curve can shift based on several factors including changes in production costs (e.g., raw materials and labor costs), technological progress, the level of competition and number of sellers/producers, and the regulatory & tax environment.
Demand is influenced by the amount of disposable income available to consumers along with consumer preferences. The presence of viable substitutes or alternatives can also shift the demand curve.