EECM1514: Introduction to Microeconomics Exam Notes

EECM1514: Introduction to Microeconomics is the foundational course for understanding how individuals and firms make choices under scarcity, how markets coordinate those choices through prices, and how policy changes affect economic outcomes. These exam notes focus on the core microeconomic toolkit—demand and supply, elasticity, consumer and producer theory, market structures, and welfare—using examples that match the kinds of contexts often emphasized in South African university, college, and TVET curricula. By the end of these notes, you should be able to model typical exam scenarios, interpret graphs, apply microeconomic reasoning step-by-step, and check your answers for economic consistency.

EECM1514 Foundations: Scarcity, Choice, and the Microeconomic Method

Microeconomics studies decision-making by households (consumers) and firms (producers), and how their interactions determine prices and quantities in specific markets. It focuses on “small-scale” economic units, but those decisions aggregate into real outcomes such as affordability, employment, firm survival, and the competitiveness of local industries.

What “microeconomics” means in exam language

In exams, microeconomics questions often look like one of these types:

1. Explain: Define concepts (e.g., opportunity cost, elasticity, marginal utility).
2. Graph: Draw and interpret demand/supply shifts or cost curves.
3. Calculate: Compute elasticities, total revenue changes, producer/consumer surplus, or equilibrium.
4. Apply: Predict the effects of a tax/subsidy/rent control/trade policy.
5. Compare: Contrast market structures (perfect competition vs monopoly vs oligopoly).
6. Evaluate: Discuss efficiency and welfare, including deadweight loss.

Your answers typically score well when you:

• Use correct definitions,
• Show reasoning using cause-and-effect,
• Use correct diagram interpretation (shift vs movement),
• Apply the correct formula and sign conventions,
• Conclude with a clear outcome (price up/down, quantity up/down, welfare impacts).

Core economic principles: assumptions you should remember

Microeconomic reasoning relies on several core principles. Even if exams do not explicitly ask for them, they often implicitly assume them.

Scarcity and opportunity cost

• Scarcity means resources are limited relative to wants.
• Opportunity cost is the value of the best alternative you give up when choosing one option.

Example (South African context):
A TVET student has limited time and money. If they work extra shifts to earn income, the opportunity cost may be lost study time (potentially lower exam performance). Microeconomics treats that as a trade-off, not merely a personal choice.

Rational choice and marginal thinking

Microeconomics often assumes agents choose actions by comparing marginal benefits (MB) and marginal costs (MC).

• Choose the level where MB ≥ MC, until MB falls to MC.
• In many models, the “optimal choice” is where MB = MC (interior solutions).

Example:
A small shopkeeper decides how many units of stock to order. The “marginal unit” decision compares:

• extra revenue from selling one more unit,
• against the extra cost of purchasing that unit and storing it.

Ceteris paribus (all else equal)

When you draw a shift in a graph, you assume other factors remain constant. If an exam question lists multiple changes, you must identify which changes move the curve and which change shift it.

Microeconomic method: from variables to model

Microeconomic exam questions often include:

• A demand or supply function,
• A statement about preferences, costs, policies, or market conditions,
• A request to find equilibrium, welfare, or elasticities.

A reliable method:

1. Identify the market (e.g., bread in a local area, phone data plans, bus fares, student accommodation).
2. Write the relationships:
   • Demand depends on price and other factors.
   • Supply depends on price and other factors.
3. Decide whether it’s a movement or a shift:
   • Movement along demand: price changes only.
   • Shift in demand: income, tastes, substitute/complement prices, expectations change.
4. Compute equilibrium:
   • Set quantity demanded equal to quantity supplied.
5. Apply the policy shock:
   • Tax changes effective prices and incentives, often leading to a wedge between consumer and producer prices.
6. Interpret welfare:
   • Use surplus concepts and deadweight loss.

How to interpret typical exam graphs

Graphs are often the highest mark area for micro papers, so the interpretation must be consistent.

Demand and supply basics

• Demand curve slopes downward: as price falls, quantity demanded rises.
• Supply curve slopes upward: as price rises, quantity supplied increases.

Key distinctions:

• Movement along the curve occurs due to a price change.
• Shift occurs due to non-price determinants.

Example: interpreting a price floor

Suppose a government sets a price floor above equilibrium (e.g., rent or minimum price for a commodity).

• If the price floor is above equilibrium, quantity supplied exceeds quantity demanded.
• That creates a surplus (excess supply), such as unsold inventory or vacant rental units (depending on the market).

A mini case study: local taxi market and scarcity of routes

Imagine a commuter taxi market where demand depends on:

• number of commuters,
• time costs,
• alternative transport availability (e.g., trains or buses).

Supply depends on:

• fuel prices,
• driver wages,
• number of licensed taxis available.

If fuel prices rise, supply decreases (shift left), which increases prices and reduces quantity. The key micro reasoning is:

• inputs become more expensive → fewer rides supplied → price rises → riders reduce demand (or switch transport modes).

This kind of story is common in micro exams because it links real constraints (fuel, licensing, time) to curves.

EECM1514 Demand, Supply, and Elasticity: Market Responses and Quantitative Exam Skills

Demand and supply analysis is the backbone of the course. Many exam problems are “policy prediction” questions that reduce to: how do prices and quantities respond when incentives change?

Demand: determinants and curve shifts

A household’s demand for a good depends on:

1. Own price (P): inverse relationship with quantity demanded.
2. Income (Y):
   • Normal goods: demand increases when income increases.
   • Inferior goods: demand decreases when income increases.
3. Prices of related goods:
   • Substitutes (cross-price positive): demand rises when substitute price rises.
   • Complements (cross-price negative): demand falls when complement price rises.
4. Tastes and preferences: advertising, trends, cultural changes.
5. Expectations: if consumers expect future price increases, current demand rises.
6. Number of buyers: market size effect.

Demand function notation

Often exams use simplified forms:

• (Q_d = a – bP) or
• (Q_d = a – bP + cY)

Where you must keep signs correct.

Supply: determinants and curve shifts

Supply depends on:

1. Own price: higher price increases quantity supplied.
2. Input costs (wages, raw materials): higher costs shift supply left.
3. Technology: improved technology shifts supply right (lower marginal cost).
4. Taxes/subsidies: taxes reduce supply (left), subsidies increase supply (right).
5. Number of sellers and capacity constraints.
6. Expectations: firms may change production if they expect future higher prices.

Equilibrium: solving quickly and correctly

Market equilibrium occurs when:
[
Q_d(P) = Q_s(P)
]
At equilibrium:

• planned demand equals planned supply,
• there is no systematic pressure for prices to change.

Example: solving an equilibrium with linear functions

Assume:

• Demand: (Q_d = 120 – 2P)
• Supply: (Q_s = 20 + 3P)

Set equal:
[
120 – 2P = 20 + 3P
]
[
100 = 5P
]
[
P^* = 20
]
Then:
[
Q^* = 120 – 2(20) = 80
]

Exam habit: show the algebra and label the equilibrium clearly: (P^) and (Q^).

Shocks: policy and real-world changes

Most exam questions describe a change in one determinant—like income, input prices, taxes—and ask you to predict new equilibrium.

Example: income increase for a normal good

If income increases and the good is normal:

• demand curve shifts right (increase in demand at every price),
• equilibrium price rises,
• equilibrium quantity rises.

If it is an inferior good:

• demand shifts left,
• equilibrium price falls and quantity falls.

Counterpoint to remember:
In some cases, equilibrium price might rise or fall in a way that depends on supply elasticity. But for a simple “demand shift right” with upward supply, the typical result is price up and quantity up.

Elasticity: measuring responsiveness

Elasticity quantifies how sensitive quantity demanded or supplied is to changes in a variable (usually price).

Price elasticity of demand (PED)

[
PED = \frac{%\Delta Q_d}{%\Delta P}
]
Typically PED is negative because of the inverse relationship between P and Q. Exams often use absolute values when interpreting magnitude.

Interpretation:

• (|PED| > 1): elastic demand (responsive)
• (|PED| = 1): unit elastic
• (|PED| < 1): inelastic demand

Key implications for total revenue (TR)

Total revenue is (TR = P \times Q).

For a price increase:

• If demand is elastic ((|PED|>1)): quantity falls a lot → TR decreases
• If demand is inelastic ((|PED|<1)): quantity falls a little → TR increases

This logic is a frequent exam marking point because it connects elasticity to revenue outcomes for firms.

Numerical example: compare revenue effects

Suppose price increases from R10 to R12 (20% increase). If demand is elastic and quantity decreases by 30%:

• TR changes by approximately (+20% – 30% = -10%) → revenue falls.

If demand is inelastic and quantity decreases by 10%:

• TR changes by approximately (+20% – 10% = +10%) → revenue rises.

Elasticity of supply (PES)

[
PES = \frac{%\Delta Q_s}{%\Delta P}
]

• High elasticity of supply: firms can adjust output quickly.
• Low elasticity: production is constrained (e.g., short-run capacity limits), so quantity changes less.

Real-world link (South Africa):
If a commodity relies on seasonal production (e.g., agricultural output), supply may be relatively inelastic in the short run.

Factors that determine elasticity

Demand elasticity depends on:

1. Availability of substitutes
2. Necessity vs luxury
3. Time horizon (elasticity often increases over time)
4. Share of income spent on the good

Example: prepaid data vs electricity

• Prepaid data plans may have substitutes (Wi-Fi, cheaper carriers), so demand may be more elastic.
• Basic electricity for many households may be more necessary, making demand less elastic in the short run (though long run may allow efficiency improvements).

Supply elasticity depends on:

• ability to change production inputs,
• time period,
• spare capacity.

Graph-based elasticity interpretation

Exams may ask you to use the slopes of curves or classify elasticity using geometry:

• A flatter demand curve tends to be more elastic.
• A steeper demand curve tends to be more inelastic.

But exact numerical elasticity requires given functions or data.

Worked policy example: tax incidence

Suppose a per-unit tax (t) is imposed on sellers. Even though the tax is “on producers,” prices paid by consumers usually rise and prices received by producers fall. The split depends on elasticities:

• More elastic side bears more tax burden.

Exam structure for tax incidence

1. Explain tax wedge: difference between consumer price (P_c) and producer price (P_p):
   [
   P_c – P_p = t
   ]
2. Use elasticity to determine who bears more:
   • more inelastic → less ability to avoid tax → larger burden.
3. Predict equilibrium:
   • quantity decreases from pre-tax equilibrium.
4. Interpret welfare:
   • government revenue vs consumer/producer surplus loss.
   • deadweight loss from reduced mutually beneficial trades.

South African oriented case: petrol price shocks and demand

Consider fuel in South Africa:

• Short run: demand for petrol is relatively inelastic due to few immediate substitutes (people still must travel).
• Long run: demand becomes more elastic due to changes like:
  • switching to public transport,
  • buying more fuel-efficient vehicles,
  • changing work locations.

An exam question might provide a story:

• fuel tax increases,
• petrol price rises,
• predicted quantity response depends on elasticity.

You should state:

• If demand is inelastic, total spending on fuel rises (all else equal).
• If supply is inelastic (or dominated by global prices), the tax effect may mainly increase consumer prices.

Common exam errors to avoid

• Confusing shift with movement (price changes vs non-price changes).
• Using elasticity signs incorrectly (usually use absolute values for magnitude).
• Forgetting that tax reduces quantity traded in standard supply-demand analysis.
• Predicting welfare changes without referencing the supply-demand surplus framework.

EECM1514 Consumer Behaviour, Utility, and Demand: From Preferences to Market Outcomes

After foundational market analysis, microeconomics moves into “how we get demand from choices.” In many curricula, consumer theory links preferences, utility maximization, and the demand curve.

Utility and preferences: what they mean

Utility

Utility is a representation of satisfaction/benefit from consuming goods. In exams, you typically treat utility as:

• ordinal (ranking of preference bundles),
• not necessarily measurable in absolute terms.

Preferences and choice assumptions

Standard assumptions include:

• Completeness: any two bundles can be compared.
• Transitivity: if A preferred to B and B preferred to C, then A preferred to C.
• Non-satiation: more of a good is preferred (at least up to relevant ranges).

Indifference curves: interpreting preference structure

An indifference curve shows combinations of two goods that give the consumer equal utility.

Properties:

1. Higher curve = higher utility (assuming monotonicity).
2. Indifference curves usually slope downward (more of one requires less of the other).
3. Typical curvature: convex to the origin (diminishing marginal rate of substitution).

Marginal rate of substitution (MRS)

MRS is how much of good Y a consumer gives up to get one more unit of good X while staying on the same utility level.

In a typical setup, exam questions connect MRS to marginal utility:
[
MRS_{X,Y} = \frac{MU_X}{MU_Y}
]

Budget constraint: affordability under prices and income

If prices are (P_X) and (P_Y) and income is (I), budget constraint is:
[
P_X X + P_Y Y = I
]
In graph form:

• intercepts show how much you can buy if you spend all income on one good.
• slope equals (-P_X/P_Y).

Utility maximization: the tangency principle

At the optimal choice:

• indifference curve is tangent to budget line,
• slope of indifference curve equals slope of budget line:
  [
  MRS_{X,Y} = \frac{P_X}{P_Y}
  ]
  This is the core exam statement: the consumer chooses the bundle where the trade-off matches the market trade-off implied by prices.

Corner solutions

Sometimes the optimum occurs at a corner:

• consumer spends only on one good,
• indifference curves might not be tangent to the budget line before reaching boundary.

Exams may ask whether a solution is interior or corner based on preference shape.

From individual demand to market demand

A market demand curve is typically built by horizontal summing individual demands (in simple cases). Even if your exam doesn’t require that exact operation, it’s useful to understand:

• more consumers → market demand increases (shifts right).
• changes in preferences or income for many consumers → shifts.

Marshallian demand and demand curve intuition

Marshallian demand shows how quantity demanded changes with price, holding income and other preferences constant.

To connect theory to the earlier “demand curve” section:

• A consumer chooses less when price rises (substitution and income effects jointly explain this under typical conditions).

Substitution and income effects (advanced but often tested)

When the price of one good changes, demand typically changes due to two effects:

1. Substitution effect: consumers replace the good with relatively cheaper alternatives.
2. Income effect: the price change changes purchasing power.

In normal goods, both effects typically reinforce each other:

• price rises → income effect reduces consumption → quantity demanded falls.

In inferior goods, income effect can oppose substitution effect, potentially creating unusual cases.

Concrete example: staple vs luxury goods in a South African setting

Consider two goods:

• Pap (staple) as a normal/inferior-type candidate depending on household needs,
• Restaurant meals as likely luxury.

If household income falls (e.g., during unemployment):

• demand for restaurant meals likely drops significantly (more responsive).
• demand for pap may fall less or could remain stable, reflecting necessity.

This is a micro explanation behind why elasticities differ.

Linking to elasticity and total revenue

Once you derive or interpret consumer demand behavior, you can connect elasticity to demand sensitivity:

• If consumers view restaurant meals as easy to substitute away from (e.g., cooking at home), demand becomes more elastic.
• If pap is hard to substitute in the short run, demand becomes more inelastic.

Producer and consumer surplus tie-in

Even though consumer theory begins with utility, the welfare framework re-expresses outcomes in measurable terms:

• consumer surplus (benefit from paying less than willingness to pay),
• producer surplus (benefit from selling above costs),
• total welfare and efficiency.

These become central for exam questions about taxes and price controls.

Common pitfalls in consumer theory questions

• Treating utility as measurable cardinal numbers without given information.
• Confusing MRS with marginal utility directly (they relate but are not identical).
• Failing to interpret tangency correctly (slope equality).
• Forgetting budget constraint defines feasible sets.

EECM1514 Firms, Costs, Market Supply, and Market Structures: Competition, Monopoly, and Welfare

A major portion of microeconomics exams assesses firm behaviour: how firms choose output and how market structure affects prices and welfare. These notes emphasize the standard cost/production logic and then build to market structures.

Firm goals: profit maximization

In many intro micro courses, firms aim to maximize profit:
[
\pi = TR – TC
]
where:

• (TR = P \times Q),
• (TC) is total cost.

Profit depends on demand conditions (price) and cost structure (technology and input prices).

Cost curves: interpreting the shape and meaning

Key cost concepts:

1. Fixed cost (FC): constant regardless of output (e.g., rent for premises).
2. Variable cost (VC): changes with output (e.g., labour hours, materials).
3. Total cost (TC):
   [
   TC = FC + VC
   ]
4. Average costs:
   • Average fixed cost: (AFC = FC/Q)
   • Average variable cost: (AVC = VC/Q)
   • Average total cost: (ATC = TC/Q)
5. Marginal cost (MC): extra cost of producing one more unit:
   [
   MC = \Delta TC / \Delta Q
   ]

Relationship between ATC and MC (very testable)

• MC crosses ATC at its minimum (typical for many cost shapes).
• If MC is below ATC, ATC is falling; if MC is above ATC, ATC is rising.

Production and marginal reasoning

Even if production functions are not always required, exams may ask you to identify:

• diminishing marginal returns,
• how marginal cost behaves as output rises.

Profit maximization and the role of marginal analysis

A standard rule:

• Choose output where marginal revenue (MR) = marginal cost (MC), provided it produces a maximum (not minimum).
• Then check whether the firm produces in the short run (shutdown rule) based on AVC.

Competitive firms (perfect competition)

In perfect competition:

• firms are price takers: market price (P) is given.
• MR equals price: (MR = P).
• The demand facing a firm is perfectly elastic.

Profit-maximization rule becomes:

• produce where (P = MC).

Shutdown rule (short-run)

If the firm cannot cover variable costs, it shuts down:

• produce if (P \ge AVC),
• shutdown if (P < AVC).

Industry supply and market outcomes

In perfect competition:

• market supply is the horizontal sum of individual firm supplies.
• entry and exit in the long run drive economic profits to zero (in many standard models).

Monopoly: market power and pricing

A monopolist faces the market demand curve and chooses output to maximize profit.

In monopoly:

• MR is below price (MR < P) due to downward sloping demand.
• The monopolist chooses output where MR = MC.
• Price is found from the demand curve at that chosen quantity.

Monopoly outcomes compared to competition

• Monopoly typically produces less output and charges higher price than perfect competition (in standard models).
• Welfare analysis:
  • Monopoly creates deadweight loss due to reduced trades that would have benefited consumers and producers.
  • It transfers surplus from consumers to the firm (and potentially to shareholders).

Welfare concepts: efficiency and deadweight loss

Using surplus framework:

• Consumer surplus: willingness to pay minus price paid.
• Producer surplus: price received minus marginal cost (or supply representation).
• Total surplus equals consumer surplus + producer surplus (ignoring externalities).

Deadweight loss arises when price differs from marginal cost and some mutually beneficial trades are not made.

Policy relevance: taxes and price controls through welfare

If the government imposes a tax:

• price to consumers rises,
• price received by producers falls,
• quantity decreases,
• government revenue equals tax rate times quantity traded,
• part of lost surplus becomes deadweight loss.

If a price ceiling is set below equilibrium:

• quantity demanded exceeds quantity supplied,
• shortages occur,
• welfare usually decreases (unless demand is mis-specified or there are additional constraints).

Oligopoly and strategic behaviour (intro level)

Even in intro micro, oligopoly may appear conceptually.

Characteristics:

• few firms dominate,
• firms’ decisions are interdependent,
• output and pricing involve strategic considerations.

Common models discussed include:

• Cournot (quantity competition),
• Bertrand (price competition),
• game-theoretic reasoning (often basic).

Case study: telecom data markets and market structure logic

A simplified view:

• If a market had many small resellers and no one had control over pricing, it could resemble competitive supply conditions.
• If one firm dominates national infrastructure and brand distribution, it resembles monopoly or monopoly-like pricing (subject to regulation and competition policy).
• If only a few providers exist (e.g., major network operators), oligopoly reasoning applies: when one firm adjusts pricing or data bundles, others respond.

Exam questions may ask:

• Would a higher price be associated with greater deadweight loss under monopoly than competition?
• Would elasticity differ across market structure due to substitutes, branding, and switching costs?

Consistency check: connecting costs to supply

A firm’s supply depends on costs and the decision to produce. Under competitive conditions, the marginal cost curve above AVC becomes the firm’s supply curve in the short run. Therefore:

• if input costs rise,
• MC shifts up,
• supply decreases,
• equilibrium price increases (if demand is downward sloping).

Common exam mistakes in firm and market structure questions

• Claiming monopoly always maximizes welfare (it usually reduces total surplus relative to competitive outcome).
• Mixing up MR and P in monopoly (MR < P).
• Ignoring shutdown/AVC rule in short-run competitive firm problems.
• Forgetting that in perfect competition, MR = P for the individual firm.

EECM1514 Microeconomic Welfare, Market Failure, and Policy Tools: Taxes, Subsidies, and Regulation

The final layer of microeconomics moves from prediction to evaluation: when markets work, when they fail, and what policies might improve outcomes. Exams often emphasize welfare analysis and efficiency under different policy interventions.

Efficiency and the logic of welfare

In standard models without externalities or information problems:

• competitive markets can be efficient (productive and allocative efficiency).
• allocative efficiency means resources allocated so that marginal benefit equals marginal cost.

A common efficiency benchmark:

• Under perfect competition, (P = MC) and (with demand as marginal benefit) yields allocative efficiency.

Externalities: when private decisions differ from social costs/benefits

Externalities occur when the actions of one party affect others without compensation.

Negative externality example

Pollution from a factory creates costs for society not reflected fully in private production decisions.

• Social marginal cost (SMC) exceeds private marginal cost (PMC).
• Market equilibrium quantity exceeds socially optimal quantity.
• Welfare loss occurs because too much output is produced.

Policy tools:

• Pigouvian tax equal to the external damage per unit.

Positive externality example

Education increases productivity and benefits others through spillovers.

• Social marginal benefit exceeds private marginal benefit.
• Underproduction occurs.

Policy tools:

• Subsidy to encourage more production/consumption.

Information failures and market outcomes (intro)

Even if not heavily detailed, micro exams may mention:

• asymmetric information (one party knows more),
• moral hazard (after contract, behaviour changes),
• adverse selection (before contract, risk types self-select).

These can lead to inefficient outcomes where markets may not reach the efficient quantity without regulation.

Taxes and subsidies: detailed welfare mechanics

Per-unit tax on a good

Let:

• equilibrium with no tax is (Q_0),
• tax reduces quantity to (Q_t),
• consumer price rises to (P_c),
• producer price falls to (P_p),
• tax revenue to the government is (t \times Q_t).

Welfare impacts:

• Consumers lose consumer surplus.
• Producers lose producer surplus.
• Government gains revenue (not “net welfare” unless you also value public spending outcomes).
• Deadweight loss equals lost surplus from reduced trade beyond transfer.

Interpreting who bears the tax burden

Tax incidence depends on elasticity:

• The more inelastic side bears more.
• The more elastic side can reduce quantity demanded/supplied more effectively.

This is consistent with supply-demand logic:

• steep demand (inelastic): consumers cannot easily reduce quantity → more burden.
• steep supply (inelastic): producers cannot easily adjust → more burden.

Subsidy: common exam reasoning

A subsidy encourages consumption or production depending on who receives it. In standard demand-supply analysis:

• A production subsidy shifts supply right.
• Equilibrium quantity increases.
• Price paid by consumers falls.
• Price received by producers rises.

Welfare impacts:

• Transfers from government (fiscal cost) to producers/consumers.
• Potential deadweight loss if subsidy encourages consumption beyond the efficient level (especially if externalities are absent).

If the good has a positive externality, a subsidy can increase total welfare.

Price controls: ceilings and floors with welfare and non-welfare consequences

Price ceilings (rent control)

If set below equilibrium:

• shortage occurs,
• quantity demanded exceeds quantity supplied,
• the “missing” trades are not just welfare losses; they can lead to rationing mechanisms like queues, informal payments, or reduced quality.

In exams, welfare loss is usually illustrated as reduced total surplus. Additional real-world harms may earn marks if the question asks for examples.

Price floors (minimum wage or minimum prices)

If set above equilibrium:

• surplus occurs,
• quantity supplied exceeds quantity demanded.
• In labour markets, minimum wage can reduce employment or change job composition depending on elasticity.

But micro exams also often ask about nuance:

• Not all minimum wages reduce employment in a simple way if the labour market is not perfectly competitive, if there are frictions, or if productivity changes.

Trade and global market effects (intro micro)

Even without heavy international economics, basic micro ideas apply to:

• tariffs,
• import quotas,
• exchange-rate induced price changes.

Example logic:

• A tariff on imports increases the domestic price.
• Domestic producers expand output.
• Domestic consumers reduce consumption.
• Some surplus transfers from consumers to domestic producers and government (tariff revenue), with deadweight loss from reduced total trade.

Market failure diagnosis checklist (exam-friendly)

When asked “Does the market failure justify intervention?” you can use a structured approach:

1. Identify the failure:
   • Externality? Information? Market power? Public goods?
2. Determine direction of inefficiency:
   • Overproduction or underproduction (for externalities).
3. Estimate whether private and social incentives differ:
   • compare MB and MC socially vs privately.
4. Select policy:
   • tax/subsidy for externalities,
   • regulation/corrective policy for information failures,
   • competition policy for market power.
5. Discuss limitations:
   • implementation costs,
   • administrative feasibility,
   • potential unintended consequences.
6. Conclude on welfare:
   • is it likely to increase total surplus?

A numerical welfare illustration (tax with surplus and deadweight loss)

Consider a simplified market:

• Without tax, equilibrium is at (Q_0 = 100).
• With a tax, quantity falls to (Q_t = 80).
• Suppose the tax creates transfers and welfare loss:
  • Consumer surplus loss = R120
  • Producer surplus loss = R80
  • Government revenue = R140
  • Deadweight loss = (CS loss + PS loss − revenue) = 120 + 80 − 140 = R60

Even if your exam doesn’t provide these exact numbers, the procedure is what matters.

South African policy examples tied to micro reasoning

Micro exam questions often expect policy examples to sound relevant to the local context. Here are typical themes and how to reason:

Food prices and market interventions

For staples:

• If demand is inelastic, taxes or shocks may strongly affect consumer expenditure.
• Price interventions (ceilings, subsidies) can shift equilibria but may produce shortages if misaligned with market-clearing levels.

Energy prices and externality thinking

If energy use has externalities (pollution/health costs):

• A tax approximating marginal external damage can move the market toward the socially optimal output/consumption.
• If the government instead subsidizes energy without addressing external costs, consumption rises, likely worsening welfare.

Housing and rent regulations

Housing markets can face:

• externalities (neighbourhood effects),
• limited supply responsiveness (inelastic short-run supply),
• information issues and discrimination.

Thus, welfare effects of rent controls depend heavily on supply elasticity and the ability of housing supply to adjust.

Writing strong exam answers: structure and marks

When answering a welfare/policy question, a high-scoring structure is:

1. State the market outcome (equilibrium price and quantity directionally).
2. Describe policy mechanism (what shifts where).
3. Predict new equilibrium:
   • price to consumers/producers,
   • quantity traded.
4. Quantify welfare conceptually:
   • show transfers and deadweight loss.
5. Conclude:
   • whether policy likely improves efficiency and why.

Common counter-arguments and “evaluation” marks

If the question asks to “evaluate” or “discuss,” include at least one counterpoint such as:

• Taxes can reduce consumption but raise administrative burdens and political resistance.
• Subsidies can be fiscally expensive and may create distortions if externalities are not present.
• Price controls can reduce welfare if they create shortages or reduce incentives to produce/maintain quality.
• Market power might require competition policy rather than price regulation alone.

A good exam response balances the core micro model with realistic limitations.

EECM1514 Quick Reference: Key Formulas, Graph Rules, and Exam Checklists

This section consolidates the most frequently used tools in a compact but rigorous way, designed for last-minute revision and rapid exam execution.

Core formulas

• Consumer surplus (conceptual): area between demand curve and price, up to quantity.
• Producer surplus (conceptual): area between price and supply/marginal cost up to quantity.
• Tax wedge:
  [
  P_c – P_p = t
  ]
• Profit:
  [
  \pi = TR – TC
  ]
• Marginal cost:
  [
  MC = \Delta TC / \Delta Q
  ]
• Elasticity of demand:
  [
  PED = \frac{%\Delta Q_d}{%\Delta P}
  ]
• Elasticity of supply:
  [
  PES = \frac{%\Delta Q_s}{%\Delta P}
  ]
• Budget constraint:
  [
  P_X X + P_Y Y = I
  ]
• Utility maximization tangency:
  [
  MRS_{X,Y} = \frac{P_X}{P_Y}
  ]

Graph “movement vs shift” checklist

• If the question says “price of the good changes” → move along the curve.
• If the question says “income changes” → shift demand (direction depends on normal vs inferior).
• If the question says “price of a substitute/complement changes” → shift demand.
• If the question says “input costs/technology/tax/subsidy changes” → shift supply.
• If the question says “tax imposed per unit” → both price sides change and quantity falls (standard partial equilibrium logic).

Market structure quick comparison

Feature	Perfect Competition	Monopoly	Oligopoly
Number of firms	Many	One dominant	Few
Firm demand curve	Perfectly elastic	Downward sloping	Depends on model
MR relative to P	(MR = P)	(MR < P)	Interdependent
Output rule	(P = MC)	(MR = MC)	model-specific
Typical efficiency	High (allocative)	Lower (deadweight loss)	varies

Welfare and policy decision checklist

When asked whether a policy improves welfare:

• Identify the problem: externality, market power, information, public goods, or distortions.
• Predict how incentives change: tax increases cost, subsidy lowers effective cost, regulation constrains actions.
• Compare private vs social marginal values.
• Explain deadweight loss and transfers.
• Mention implementation limitations.

Final Exam Readiness: Practice-Style Scenarios (with Reasoning Templates)

Even without answering a full set of past papers, you can train exam performance by using reasoning templates and applying them to plausible scenarios.

Scenario 1: Subsidy for a transport mode with limited alternatives

Question style: Government subsidizes commuter rail tickets. Predict price, quantity, and welfare.

Reasoning template:

1. Subsidy shifts supply of the service or reduces effective price to consumers.
2. New equilibrium:
   • Quantity increases.
   • Consumer price falls (or producer price received rises, depending on subsidy type).
3. Welfare:
   • If externalities or public good elements exist (e.g., reduced congestion/pollution), subsidy can improve efficiency.
   • Otherwise, it may cause overconsumption relative to marginal social benefit and create deadweight loss.

Scenario 2: Minimum price for agricultural products

Question style: A minimum price is imposed above equilibrium for a commodity.

Reasoning template:

1. Price floor above equilibrium creates surplus.
2. Quantity supplied > quantity demanded.
3. Welfare:
   • some trades prevented,
   • deadweight loss arises.
4. Non-welfare effects:
   • storage costs, spoilage, rationing.

Scenario 3: Tax on sugary drinks

Question style: A per-unit tax is imposed. Consider elasticities.

Reasoning template:

1. Tax wedge reduces quantity.
2. Determine tax incidence:
   • more inelastic side bears more burden.
3. Welfare:
   • revenue increases government funds,
   • consumption falls (potential welfare improvement if negative externality/health externality exists),
   • deadweight loss depends on demand/supply elasticities.

Scenario 4: Monopoly in a locally concentrated industry

Question style: A single firm dominates the sale of a product with no close substitutes. Explain welfare impacts.

Reasoning template:

1. Monopoly chooses output where (MR = MC).
2. Price set above marginal cost.
3. Output lower than competitive benchmark.
4. Deadweight loss:
   • reduced consumer/producer surplus compared with efficient outcome.
5. Possible policy:
   • regulation, competition law, or price caps (with cautions).

These exam notes cover the essential microeconomic foundations, quantitative tools (elasticity, equilibrium, surplus/welfare), and the conceptual bridge from consumer and producer theory to market structures and policy evaluation. If you can consistently: identify the curve shifts correctly, compute equilibrium carefully, interpret elasticity consequences, apply marginal analysis in firm problems, and justify welfare conclusions, you will be well prepared for the style of questions typically used in EECM1514 assessments across South African universities, colleges, and TVET offerings.