Overview
This lecture explains the concept of supply in economics, including its definition, features, factors affecting supply, the law of supply, exceptions, elasticity, graphical representation, and related key terms.
Meaning and Definition of Supply
- Supply is the quantity of a commodity that a firm is willing and able to offer for sale at a given price during a specific period.
- Supply is a flow concept, measured over a period of time (such as a day, week, month, or year).
- Stock refers to the total quantity of goods a firm possesses at a particular point in time, while supply is the portion of stock the firm is willing to sell.
- The difference between stock and supply: stock is the total available, but supply is what the seller is ready to offer for sale at current prices.
Factors Affecting Supply
- Price of the given commodity: Higher prices generally lead to higher supply, as sellers are motivated by greater profit.
- Price of other goods: If the price of a related or alternative good rises, the supply of the current good may decrease as producers switch to the more profitable option.
- Prices of factors of production: Increased costs (like labor, rent, or raw materials) reduce supply, while lower costs increase it.
- State of technology: Improved or updated technology increases supply by making production more efficient; outdated technology reduces supply.
- Taxes: Higher taxes decrease supply by reducing profit margins; lower taxes increase supply.
- Goals/objectives of the firm: Firms aiming to maximize profit will increase supply; other objectives may affect supply differently.
- Number of firms: More firms in the market increase total supply; fewer firms reduce it.
- Future price expectations: If sellers expect prices to rise in the future, they may reduce current supply to sell later at higher prices; if they expect prices to fall, they may increase current supply.
- Transport and infrastructure: Better transportation and infrastructure make it easier to supply goods, increasing supply.
Individual vs. Market Supply
- Individual supply: The quantity of a commodity supplied by a single firm at different prices.
- Market supply: The total quantity supplied by all firms at different prices, found by horizontally summing individual supplies.
- Market supply is influenced by the number of firms, their expectations, and the means of transport and communication.
Supply Schedule and Supply Curve
- Supply schedule: A table showing the quantities of a commodity supplied at various prices during a given period.
- Individual supply schedule: Shows quantities supplied by one producer at different prices.
- Market supply schedule: Shows total quantities supplied by all producers at different prices.
- Supply curve: A graphical representation of the supply schedule, typically upward sloping, showing the direct relationship between price and quantity supplied.
- The market supply curve is flatter than the individual supply curve because the proportionate change in market supply is greater.
Law of Supply
- The law of supply states that, ceteris paribus (all other factors held constant), there is a direct relationship between the price of a commodity and the quantity supplied.
- As price increases, quantity supplied increases; as price decreases, quantity supplied decreases.
- The law assumes other factors (like technology, input prices, taxes, etc.) remain unchanged.
Exceptions to the Law of Supply
- Future price expectations: If sellers expect prices to fall, they may increase current supply to avoid losses.
- Agricultural products: Supply may not increase with price due to factors like weather, pests, or natural disasters.
- Perishable goods: Short shelf-life limits the ability to hold stock, so supply may not increase with price.
- Rare articles: Unique or rare items cannot have their supply increased, regardless of price.
- Backward countries: Limited resources or poor infrastructure restrict the ability to increase supply.
Changes in Supply: Movement and Shift
- Movement along the supply curve (expansion/contraction): Caused by a change in the price of the commodity itself, with all other factors held constant.
- Expansion in supply: Increase in quantity supplied due to a price increase (upward movement along the curve).
- Contraction in supply: Decrease in quantity supplied due to a price decrease (downward movement along the curve).
- Shift in the supply curve (increase/decrease): Caused by changes in non-price factors (such as technology, input costs, taxes, etc.), with price held constant.
- Increase in supply: Supply curve shifts to the right due to favorable changes (e.g., improved technology, lower input costs).
- Decrease in supply: Supply curve shifts to the left due to unfavorable changes (e.g., higher taxes, outdated technology).
Price Elasticity of Supply
- Definition: Measures how much the quantity supplied of a commodity responds to a change in its price.
- Formula:
Price Elasticity of Supply = (Percentage change in quantity supplied) / (Percentage change in price)
- Types of elasticity:
- Perfectly inelastic supply: Quantity supplied does not change regardless of price changes (vertical supply curve; e.g., fixed stadium seats).
- Inelastic supply: Quantity supplied changes by a smaller percentage than the price change.
- Unitary elastic supply: Quantity supplied changes by the same percentage as the price change (45° supply curve through the origin).
- Highly elastic supply: Quantity supplied changes by a larger percentage than the price change.
- Perfectly elastic supply: Any change in price leads to an infinite change in quantity supplied (horizontal supply curve).
- Elasticity is always positive for supply, as price and quantity supplied move in the same direction.
Time Period and Supply
- Market period: Very short period where supply cannot be adjusted in response to price changes (supply is fixed).
- Short run: Only variable factors of production can be changed; supply can be adjusted to a limited extent.
- Long run: All factors of production can be changed; firms can fully adjust supply in response to price changes.
Key Terms & Definitions
- Supply: Quantity of goods a firm is willing and able to sell at a specific price and time.
- Stock: Total goods available with a firm at a point in time.
- Supply Schedule: Table showing quantities supplied at various prices.
- Supply Curve: Graph showing the relationship between price and quantity supplied.
- Law of Supply: Principle stating a direct relationship between price and supply, ceteris paribus.
- Ceteris Paribus: All other factors held constant.
- Elasticity of Supply: Degree of supply response to price changes.
Action Items / Next Steps
- Review supply curve graphs and examples from the lecture to understand movement and shifts.
- Practice calculating price elasticity of supply using sample data and the percentage method.
- Prepare for questions on exceptions to the law of supply and be able to explain real-life examples.
- Study the difference between movement along the supply curve (caused by price changes) and shifts of the supply curve (caused by non-price factors).
- Familiarize yourself with key terms and be able to distinguish between stock and supply, as well as individual and market supply.