Study Notes on Price and Quantity Decision-Making

Unit Seven Overview

• Focus on firms and customers' decision-making regarding price and quantity.

• Decisions related to both price and production quantity are key.

Costs Discussion

• In-depth discussion about cost functions, classifying into three important categories:

  • Total Cost

  • Marginal Cost

  • Average Cost

Cost Function Details

• Total cost example presented as an equation: 2*q (where 'q' is quantity).

• Y-intercept interpretation: Indicates fixed costs. When quantity = 0, total costs are not zero, suggesting that fixed costs must be considered.

• Marginal Cost: Remains constant as production increases, implying fixed marginal cost.

• Fixed Costs definition: Costs that do not change with production level. Example: Overhead costs like rent.

Average Cost Analysis

• Understanding the behavior of average costs when both fixed costs and marginal costs are fixed:

  • As quantity increases, average cost decreases initially because fixed costs are spread over more units.

  • Average cost converges to marginal cost as output increases, but always remains slightly above marginal cost due to fixed costs.

Average Cost Function Rewriting

• Average cost function derived from total cost:

  • Formula: Average Cost = Total Cost / q

  • This can be expressed as AC = (f/q) + c, where 'f' is fixed cost and 'c' is variable cost.

  • As 'q' increases, (f/q) decreases, causing average cost to approach marginal cost 'c'.

Graphical Representation

• Graphical understanding:

  • Total Cost overview as a linear graph.

  • Marginal cost represented as the slope of the total cost at any point.

  • Marginal Cost = First derivative of Total Cost function.

Cost Function Examples

• Example 1 (c(q) = 2*q):

  • Statement Evaluation in context with production:

  1. No fixed costs — TRUE, since at q=0, c=0.

  2. Marginal cost of production is 2 — TRUE, since the slope is constant at 2.

  3. Average cost does not fall with output — FALSE; average cost remains constant since it's equal to marginal cost.

  4. Average cost equals marginal cost for any quantity — TRUE; both equal to 2.

Short Run vs Long Run Analysis

• Short Run: Specific period where at least one input is fixed. E.g., factory size.

• Long Run: All inputs can be adjusted, allowing for scalability of operations.

  • Example: The ability to hire more workers or purchase more machinery to adjust output.

Marginal Cost Behavior

• In short run, pushing production might lead to increasing marginal costs due to more intensive usage of fixed inputs, leading to diminishing returns. This results in a curve for marginal cost, showing upward trends.

Relationship Between Marginal Cost (MC) and Average Cost (AC)

• Marginal Cost cuts through the minimum average cost point.

• If MC is below AC, AC decreases; if MC is above AC, AC increases.

Elasticity of Demand

• Transition to demand side. Introduces elasticity as a measure of responsiveness:

  • Price Elasticity of Demand (Epsilon): Defined as
    $\epsilon = -\frac{\% \text{ Change in Quantity Demanded}}{\% \text{ Change in Price}}$

• Scenarios illustrated:

  • Unit elastic: Price change by 20%, demand change by -20%. (Epsilon = 1)

  • Elastic: Price change by +20%, demand by -50% (Epsilon > 1)

  • Inelastic: Price change by +20%, demand change by -2% (Epsilon < 1)

Factors Affecting Elasticity

• Nature of the good (necessity vs luxury)

  • Inelastic goods: Life-saving medicines, basic necessities. Demand remains despite price increase.

  • Elastic goods: Luxury items, transportation, etc; sensitive to price changes.

Demand Curve Interpretations

• Willingness to Pay (WTP): Reflects how different consumers value a product based on preferences and budget.

• Law of Demand: Ceteris Paribus, price and quantity demanded move in opposite directions; prices increase lead to demand decrease and vice versa.

Factors Influencing Price Elasticity

• Degree of necessity versus luxury.

• Availability of substitutes.

• Market Competition Level.

Specific Market Examples

• Medical products: Highly inelastic due to necessity.

• Gasoline: Inelastic in short-term as consumers adjust in the long run.

• Luxury goods: Generally elastic; demand responds strongly to price increases.

Elasticity Calculation Examples

• % Change calculation: Formula given as
  $\frac{\Delta Q}{Q_1}$

• Reciprocals: Relates slope with elasticity metrics.

Conclusion

• Review of the impact of price elasticity on different markets, emphasizing adjustment time frames and consumer behavior.

  • Sketch demand curves for insulin (inelastic) vs. cinema tickets (more elastic).