Price Mechanism & Applications – Comprehensive Study Notes

Market Economy & The Price Mechanism

  • Core idea: In a free-market (no govt. intervention) resources are allocated through the mutually-adjusting forces of demand and supply.
  • Actors & roles
    • Households → consumers of final g/s, owners of FOPs → give rise to market demand.
    • Firms → producers of g/s → give rise to market supply.
  • Necessary conditions for the textbook model
    • Perfect competition (many buyers & sellers, homogeneous product, perfect info)
    • Rational, self-interested behaviour (profit-max firms, utility-max consumers)
    • Freedom of choice & enterprise (consumer sovereignty, production freedom)
    • Private property rights
  • 3 Fundamental questions solved by prices
    1. What & how much to produce?
    2. How to produce?
    3. For whom to produce?
  • Three functions of price
    • Signalling (allocative)
    • Rationing (distributive)
    • Incentive
  • Smith’s “invisible hand”: individual pursuit of self-interest → social allocation that “tends” toward efficiency.

Demand Theory

  • Effective demand: willingness and ability to buy.
  • Law of Demand: Q_d \propto \frac1P \ (ceteris\ paribus)
    • Explained by:
    • Law of Diminishing Marginal Utility (LDMU)
    • Substitution effect
    • Income effect
  • Marginalist principle for consumers
    • Buy additional unit if MU> P; stop when MU=P.
  • Movements vs shifts
    • Movement → change in price of the good itself.
    • Shift → change in non-price determinants (T-I-P-E-N-I-E):
    • Tastes & preferences (incl. ads, fads, seasons)
    • Income (normal vs inferior)
    • Prices of related goods (substitutes/complements)
    • Expectations of future prices
    • Number & structure of buyers (population)
    • Interest rates
    • Exchange rates
  • Derived demand: input demand originating from demand for final product (e.g., steel ↔ cars).

Supply Theory

  • Definition: quantity producers willing & able to sell at each price.
  • Law of Supply: Q_s \propto P \ (ceteris\ paribus)
    • Upward slope due mainly to Law of Diminishing Marginal Returns (LDMR) → rising MC.
  • Marginalist principle for firms
    • Produce additional unit if P>MC; stop where P=MC.
  • Movements vs shifts
    • Movement → own-price change.
    • Shift → non-price determinants (C-R-E-S-T):
    • Cost of production (input prices, technology, govt. policy taxes/subsidies)
    • Related-goods prices (joint vs competitive supply)
    • Expectations of future prices / entry–exit of firms
    • State of technology / productivity
    • exogenous factors (Weather, natural shocks).
  • Joint supply (beef & leather); Competitive supply (corn for food vs corn for ethanol).

Interaction of Demand & Supply

  • Market equilibrium: Qd = Qs at P^* , Q^*; no inherent pressure to change.
  • Disequilibrium
    • Surplus (excess supply) → downward price pressure.
    • Shortage (excess demand) → upward price pressure.
  • Adjustment story (price mechanism)
    1. Identify surplus/shortage.
    2. Price signals provoke incentives (buyers reduce/increase Qd; sellers adjust Qs).
    3. Process continues until new P^, Q^.

Economic Welfare

  • Consumer Surplus (CS): \sum (WTP - P_{paid}) → area below demand & above price.
  • Producer Surplus (PS): \sum (P{received} - MC{min}) → area above supply & below price.
  • Total (social) surplus = CS+PS. Maximised at competitive equilibrium (allocative efficiency).
  • Deadweight loss (DWL) arises when Q ≠ Q^* (under- or over-production).

Price Mechanism & Economic Efficiency

  • Allocative efficiency: produce the mix that maximises society’s welfare; occurs when P = MC.
  • Productive efficiency: produce each output at lowest average cost; achieved in long-run perfect competition via factor-price signals.
  • Equity caveat: market may yield unequal distribution (for-whom).
  • Market failure cases (externalities, public goods, imperfect info, market power) motivate intervention.

Elasticities

  • General formula E_{xy}=\frac{\%\,\Delta X}{\%\,\Delta Y}.

Price Elasticity of Demand (PED)

  • PED=\frac{\%\Delta Q_d}{\%\Delta P} (negative by convention).
  • Ranges & shapes: perfectly inelastic =0; inelastic
  • Determinants: substitutes, necessity, income share, habit, time.
  • Uses
    • Predict revenue effect of price changes.
    • Gauge extent of Q & P changes when supply shifts (agri vs luxury example).

Price Elasticity of Supply (PES)

  • PES=\frac{\%\Delta Q_s}{\%\Delta P} (positive).
  • Determinants: spare capacity, inventories, factor mobility, production length, time horizon.
  • Uses: predict P-Q responses to demand shifts (oil vs electronics example).

Cross Elasticity of Demand (CED)

  • CED{AB}=\frac{\%\Delta QA}{\%\Delta P_B}.
    • Substitute → CED>0; complement → CED<0; unrelated =0.
    • Magnitude → closeness of relationship.
  • Applications: firm pricing strategy, assessing tax spill-overs (sugar tax → switch to diet drinks), antitrust definition of markets.

Income Elasticity of Demand (YED)

  • YED=\frac{\%\Delta Q_d}{\%\Delta Y}.
    • Inferior
  • Applications: forecasting sectoral growth (luxury handbags in booms, instant noodles in recession), govt planning (public housing mix).

Limitations common to all elasticities

  • Measurement errors, ceteris paribus rarely holds, static vs dynamic, ignores cost side.

Applications of Elasticities

  • Pricing decisions (monopoly/oligopoly): raise P on inelastic segments, use advertising to reduce PED.
  • Output planning: luxury-oriented firms expand capacity during expected income growth.
  • Government policy
    • Tax incidence depends on relative PED & PES.
    • Designing sin taxes (cigarettes with inelastic demand).
    • Evaluating subsidy cost-effectiveness.

Government Intervention

Indirect Taxes

  • Specific: fixed t per unit → vertical/p arallel up-shift.
  • Ad valorem: % of price → pivotal rotation.
  • Incidence: shared; consumer burden bigger when PED<PES.
  • Creates DWL area, reduces CS & PS, raises gov revenue =t\times Q_{after}.

Direct Taxes

  • Tax on income → lowers disposable Y → demand curve shifts left for normal goods.

Subsidies

  • Indirect: shifts supply down/right by s.
  • Direct (consumption): shifts demand right.
  • Gov expenditure =s\times Q_{after}; increases CS & PS but with DWL if no market failure.

Price Controls

  • Price floor (min price) above P^* → surplus; govt may purchase excess.
  • Price ceiling (max price) below P^* → shortage; leads to rationing, black markets.

Quantity Controls (Quotas)

  • Effective when set < Q^*; create artificial scarcity, raise price, transfer surplus to licence-holders.

Labour Market

  • Demand for labour derived from MRP; downward-sloping.
    • Depends on product demand, productivity, prices of other inputs, technology.
  • Supply of labour upward-sloping in aggregate; affected by population, migration, education, alternative options, non-wage perks.
  • Equilibrium wage at intersection; adjustment via surplus (unemployment) or shortage (vacancies).
  • Elasticities
    • PED_L higher when easy capital substitution, labour cost high share, elastic product demand.
    • PES_L higher with transferable skills, short training, high mobility.
  • Wage differentials explained by differences in demand, supply, elasticities, job/worker heterogeneity, unions, monopsony, discrimination, government policies (minimum wage, foreign-worker quota).
  • Case: Singapore NWC – tripartite wage guidelines signal sustainable wage growth ≤ labour productivity growth.

Limitations & Ethical / Practical Considerations

  • Perfect-competition assumptions rarely hold; real markets show power asymmetries.
  • Equity vs efficiency trade-offs (e.g., rice pledging scheme, minimum wage).
  • Behavioural departures from rationality (habit, bounded rationality).
  • Environmental & social externalities not priced (food crises, water scarcity).
  • Political economy: subsidies/tariffs driven by lobbying rather than welfare.

Quick-Reference Formula Sheet

  • PED = \left|\frac{\%\Delta Q_d}{\%\Delta P}\right|
  • PES = \frac{\%\Delta Q_s}{\%\Delta P}
  • CED = \frac{\%\Delta Q{d,A}}{\%\Delta PB}
  • YED = \frac{\%\Delta Q_d}{\%\Delta Y}
  • CS area: integral under D above P.
  • PS area: integral above S below P.

Study Checklist

  • [ ] Can I narrate the surplus → price fall → new equilibrium story fluently?
  • [ ] Can I list & apply the T-I-P-E-N-I-E and C-R-E-S-T determinants?
  • [ ] Can I compute elasticities and interpret their magnitudes & signs?
  • [ ] Can I sketch DWL for tax, subsidy, ceiling, floor, quota?
  • [ ] Can I link labour market events to wage & employment outcomes?
  • [ ] Can I evaluate policy tools against efficiency and equity criteria?