Microeconomics: Supply, its Determinants, and Related Concepts

Supply Shocks and Determinants of Supply

Supply Shocks

  • Supply shocks are non-price determinants of supply.

  • They can be either negative or positive.

    • Negative Supply Shock: An event that causes supply to decrease. For example, a week of rain before harvest or a hurricane destroying crops leads to a decrease in agricultural supply.

    • Positive Supply Shock: An event that causes supply to increase. For instance, discovering a vast new oil reserve would significantly increase the world's oil supply.

Defining Supply

  • Individual Firm Supply: Indicates the various quantities of a good or service a firm is willing and able to produce and supply to the market for sale at different possible prices.

  • Key components of any supply definition:

    • Quantity: A specific amount of a good or service.

    • Willing and Able: The firm must be both capable of producing and desirous of selling at the given price (e.g., they might be able to sell for a penny, but not willing if they lose money).

    • Different Possible Prices: Supply is always considered in relation to varying price points.

  • Less critical but present in comprehensive definitions: A particular time period and the ceteris paribus (all else equal) assumption.

The Law of Supply

  • The Law of Supply describes a direct or positive relationship between price and quantity supplied.

  • It is a conditional (if-then) statement:

    • If the price (P) of a good increases, then the quantity supplied (QS) of that good increases. (P ightarrow ext{increase}, QS
      ightarrow ext{increase}).

    • If the price (P) of a good decreases, then the quantity supplied (QS) of that good decreases. (P ightarrow ext{decrease}, QS
      ightarrow ext{decrease}).

  • Rationale: Producers are motivated to produce more of a product when its price is higher because they can make more money.

  • Graphical Representation: A typical supply curve slopes upward from left to right, visually representing this direct relationship.

Individual vs. Market Supply Curves

  • Individual Supply Curve: Represents the quantities a single firm is willing and able to supply at various prices.

    • Example: Firm 1's supply schedule at $P=1, QS=1$; at $P=2, QS=2$; at $P=3, Q_S=3$.

  • Market Supply Curve: Represents the total quantity that all firms in a particular industry are willing and able to supply at various prices.

    • Derivation: To obtain the market supply, you horizontally sum the quantities supplied by all individual firms at each specific price point.

      • Example (summing Firm 1 and Firm 2):

        • At $P=1$: Firm 1 $QS=1$, Firm 2 $QS=2
          ightarrow$ Market $Q_S=3$.

        • At $P=2$: Firm 1 $QS=2$, Firm 2 $QS=3
          ightarrow$ Market $Q_S=5$.

  • Slope Comparison: The market supply curve typically has a flatter slope (is more elastic) compared to individual firm supply curves, indicating a greater responsiveness of total quantity supplied to price changes.

Perfectly Inelastic Supply (Vertical Supply Curve)

  • A perfectly inelastic supply curve is vertical, meaning the quantity supplied remains constant regardless of price changes.

  • Real-world examples:

    • Tickets to Fixed-Capacity Events: Concerts, sporting events, or plays in a stadium with a fixed number of seats (e.g., if a stadium holds 100,000 people, you cannot sell a 100,001^{st} ticket, regardless of price).

    • Antiques and Unique Artworks: Items that can no longer be produced or whose creator is no longer alive (e.g., Picasso paintings, because Picasso cannot make new ones).

    • Certain Natural Resources: Resources that are finite and cannot be created (like naturally occurring oil, although new reserves can be discovered, and synthetic alternatives can be made). This differs from resources like trees, which can be farmed and replenished.

Perfectly Inelastic Demand (Vertical Demand Curve)

  • A perfectly inelastic demand curve is vertical, meaning the quantity demanded remains constant regardless of price changes.

  • Real-world examples:

    • Life-Saving Medications: A specific quantity of a drug (e.g., insulin for Type 1 diabetes) is needed daily by a patient, regardless of its cost, as not consuming it has critical health consequences. Patients will buy the required amount even if the price increases significantly, and won't buy substantially more if the price decreases due to storage limitations and the fixed daily need.

    • Water is sometimes suggested, but it's a less perfect example as slight variations in daily intake might not be immediately life-threatening.

Shifts vs. Movements Along the Supply Curve

  • This distinction is crucial for understanding how supply changes.

  • Movement Along the Supply Curve:

    • Cause: This happens only due to a change in the price of the good itself.

    • Effect: A change in price causes a change in quantity supplied (not referred to as a change in supply).

    • Direction: If price increases (e.g., from P1 to P2), quantity supplied increases (from Q{S1} to Q{S2}), moving up and along the curve. If price decreases, quantity supplied decreases, moving down and along the curve.

  • Shift of the Supply Curve:

    • Cause: This happens due to a change in any non-price determinant of supply.

    • Effect: A shift represents a change in supply (not quantity supplied). It means that at every possible price, the quantity supplied has either increased or decreased.

    • Direction:

      • Increase in Supply: The entire supply curve shifts right, or down, or out.

      • Decrease in Supply: The entire supply curve shifts left, or up, or in.

Non-Price Determinants of Supply (Factors Causing Shifts)

  • These factors can cause the entire supply curve to shift right (increase in supply) or left (decrease in supply).

  1. Costs of Factors of Production:

    • Factors: Land (cost: rent), Labor (cost: wages), Capital (cost: interest), Entrepreneurship (cost: profit).

    • Rule:

      • If costs of production increase, supply decreases (shifts left).

      • If costs of production decrease, supply increases (shifts right).

    • Examples:

      • A minimum wage increase (higher labor cost) would lead many companies to reduce staffing or production, causing supply to decrease.

      • Companies might leverage lower-wage labor (e.g., in overseas factories or from undocumented workers who cannot demand legal minimums) to reduce costs and increase supply.

  2. Technology:

    • Rule: Improvements in technology generally lead to an increase in supply (shifts right).

    • Explanation: While initial investment in new technology can be costly, over time, it typically enhances productivity, reduces per-unit costs, and allows firms to supply more efficiently.

    • Example: Replacing old lighting with more energy-efficient systems (e.g., LED lights) might have an upfront cost but leads to long-term cost savings and potentially increased output per unit of energy, thereby increasing supply capacity.

  3. Prices of Related Goods: Changes in the prices of other goods a firm could produce can affect the supply of the current good.

    • Competitive Supply: When a firm can produce different goods using similar resources.

      • If the price of Good 1 increases, the firm will produce more of Good 1 (increase in Q_{S1}) and decrease the supply of Good 2 (since resources are diverted).

    • Joint Supply: When the production of one good automatically results in the production of another good (byproduct).

      • If the price of Good 1 increases, leading to an increase in its quantity supplied (Q_{S1}), then the supply of Good 2 will also increase (e.g., increased milk production also increases the supply of ice cream as a byproduct).

  4. Expectations of Future Prices:

    • Rule: If producers expect the price of their product to go up in the future, they will decrease current supply (shift supply left) to sell more later at the higher price.

    • Conversely, if they expect prices to fall, they might increase current supply to sell before prices drop.

    • Consumer Analogy: Consumers also adjust based on expectations; if a big sale is expected, current demand for the item may decrease.

  5. Taxes:

    • Rule: An increase in taxes (t) on production or sales acts as an additional cost for firms, leading to a decrease in supply (shifts left).

    • Conversely, a decrease in taxes would increase supply.

  6. Subsidies:

    • Definition: Financial assistance from the government to firms, usually to encourage specific production or lower costs.

    • Rule: An increase in subsidies ( ext{sub}) reduces a firm's effective costs, leading to an increase in supply (shifts right).

    • Conversely, a decrease in subsidies would decrease supply.

  7. Number of Firms in the Market:

    • Rule: An increase in the number of firms in an industry leads to an increase in overall market supply (shifts right).

    • A decrease in the number of firms leads to a decrease in market supply.

  8. Supply Shocks: (As discussed at the beginning)

    • Can cause sudden increases or decreases in supply due to unexpected events.

Higher Level (HL) Concepts (Brief Mention)

  • Short Run vs. Long Run: Important economic distinctions regarding the flexibility of inputs and production.

  • Total Product (TP) vs. Marginal Product (MP):

    • Marginal Product: The additional output generated by adding one more unit of an input (e.g., one more worker).

  • Total Cost (TC) vs. Marginal Cost (MC):

    • The additional cost incurred by producing one more unit of output.

  • Diminishing Marginal Returns: A phenomenon where, past a certain point, adding more units of a variable input to a fixed input results in smaller increases in output (or even a decrease if inputs get in each other's way).