ECO2004S: Intermediate Macroeconomics Exam Prep

ECO2004S (Intermediate Macroeconomics) typically tests whether you can connect theory—like aggregate demand and supply, the IS–LM framework, money and inflation, labour markets, and open-economy dynamics—to the kind of quantitative and diagram-based reasoning used in exams. This study guide is built to help you answer both conceptual questions (explaining mechanisms) and applied problems (deriving relationships, interpreting graphs, and doing consistent calculations). Because exam expectations vary by South African universities and lecturer emphasis, the guide includes reusable “answer templates” and practice scenarios grounded in familiar macro models.

ECO2004S: What Exam Questions Usually Test (and How to Score High)

Intermediate macro exams often combine five broad competencies: (1) graph-based understanding, (2) equation manipulation, (3) interpretation of policy tools, (4) open-economy extensions, and (5) labour-market and price-level dynamics. Even when a question seems purely conceptual, there is usually an underlying model the examiner expects you to implicitly use.

Core model vocabulary you must recognize instantly

You should be able to see a question and immediately know which backbone model(s) it belongs to:

• Aggregate Demand (AD) and Aggregate Supply (AS)
  • AD is driven by consumption, investment, government spending, and net exports; it is typically linked to interest rates and the money market.
  • AS captures inflation dynamics and how output responds to shocks (short-run vs long-run behavior).
• IS–LM (closed economy)
  • IS: goods market equilibrium, linking output (Y) and interest rate (r) through saving/investment and equilibrium in planned spending.
  • LM: money market equilibrium, linking (Y) and (r) via money supply/demand.
• Money, inflation, and expectations
  • Common logic: monetary growth affects nominal variables; inflation depends on money growth, output gaps, and expectations.
  • You often need to distinguish short-run effects from long-run neutrality.
• Labour markets and the natural rate
  • Links: unemployment, wages, inflation, and output gaps (Phillips curve reasoning).
  • Questions may ask how policy affects employment in the short run but tends to affect inflation rather than long-run employment.
• Open economy (often IS–LM–BP or related)
  • Links: exchange rates, net exports, capital flows, trade balance, and the balance of payments.
  • Policy under fixed vs flexible exchange rates is a classic exam theme.

Diagram discipline: the fastest way to earn marks

Exams reward clarity. You don’t need artistry, but you do need structure.

A consistent diagram checklist

When you draw a diagram (IS–LM, AS–AD, or labour market), always include:

1. Axes labeled clearly
   • IS–LM: vertical (r), horizontal (Y).
   • AD–AS: vertical price level (P) (or inflation), horizontal output (Y).
2. Direction of effect (which way the curve shifts)
   • Make the shift explicit: “A rise in (G) shifts IS right.”
3. New equilibrium points
   • Label old and new equilibrium (E_0) and (E_1).
4. At least one sentence interpreting the movement
   • E.g., “Higher (Y) raises money demand, pushing (r) up; private investment falls, partially offsetting fiscal expansion.”

If you do only curve shifts without interpretation, you often lose the “mechanism” marks.

Equation discipline: what examiners love to see

For calculation/derivation questions, you should show:

1. Start from a definition (e.g., money demand equation (M/P = L(Y,r)))
2. Set equilibrium conditions (e.g., goods market: (Y = C + I + G) and (C = a + b(Y-T)))
3. Solve systematically (substitution step-by-step)
4. State comparative statics (how (Y) and (r) change when parameter increases)

Even if you don’t get the exact algebra perfect, showing a correct chain of logic helps partial credit.

Answer templates you can reuse in almost any question

Use these as exam “scripts,” adapting to the specific variable names used in your class.

Template A: Policy shock (fiscal or monetary) — closed economy

1. State the model: “In IS–LM, equilibrium is where IS and LM intersect.”
2. Identify the initial curve shift:
   • Fiscal: increase in (G) raises planned spending → IS shifts right.
   • Monetary: increase in (M) → higher real money balances (M/P) → LM shifts right.
3. Explain the mechanism:
   • Right shift raises (Y), which raises money demand; interest rate adjusts until money market clears.
4. Draw and interpret: direction for (Y) and (r).
5. Mention crowding out or offset:
   • Higher (r) reduces investment, partially offsetting fiscal impact.

Template B: Inflation / output relationship (short run vs long run)

1. Identify whether the shock is nominal (money growth, supply shock affecting prices) or real (technology).
2. Explain short-run: prices are sticky → output adjusts.
3. Explain long-run: wages/prices adjust → output returns to natural rate; inflation bears the long-run burden.

Template C: Open economy under different exchange regimes

1. Specify regime: fixed or flexible.
2. Under fixed exchange rates, central bank typically accommodates to maintain the peg.
3. Under flexible, the exchange rate adjusts, absorbing part of the shock.
4. Explain interest parity/capital flows if relevant.

Common pitfalls that lose marks (avoid these)

• Mixing up axes: IS–LM uses (r) and (Y); AD–AS uses (P) and (Y).
• Stating “money affects output in the long run” without clarifying expectations. The typical intermediate-macro answer: money is neutral long run; real effects may be temporary or depend on institutional frictions.
• Ignoring the feedback loop: for example, fiscal expansion raises (Y), which increases money demand and affects (r), which affects investment.
• Not stating direction: even if you can’t compute magnitude, always say whether (Y) rises or falls and whether (r) rises or falls.

South Africa context: how local data questions often appear

South African papers often contextualize macro relationships using familiar institutions and macro targets. Even if numbers aren’t required, examiners like you to reference plausible mechanisms:

• South Africa’s inflation targeting framework makes it common to link inflation outcomes to monetary policy decisions.
• Labour market outcomes in South Africa—such as unemployment and wage bargaining—often appear when discussing labour supply, unemployment persistence, or inflation dynamics.
• External sector: because South Africa is open, questions may ask how exchange-rate movements affect net exports and inflation.

When you answer, focus on mechanism rather than claiming exact values unless the question provides them.

ECO2004S: Closed-Economy Macroeconomics—IS–LM, AD–AS, and Policy Effects

This section builds the closed-economy core most intermediate macro exams require. The goal is not just to know definitions, but to confidently predict how shocks change equilibrium output and interest rates and then connect that to inflation and employment through labour-market logic or AS–AD.

The goods market: deriving and interpreting IS

A standard consumption–investment structure

A typical setup in intermediate macro uses:

• Consumption: (C = a + b(Y – T))
  • (a): autonomous consumption
  • (b): marginal propensity to consume (MPC), (0<b<1)
  • (T): taxes
• Investment depends negatively on interest rate: (I = \bar{I} – d r) (or similar form)
• Government spending: (G)
• Equilibrium goods market:
  [
  Y = C + I + G
  ]

Substitute:

[
Y = a + b(Y – T) + (\bar{I} – dr) + G
]

Rearrange to isolate (Y) as a function of (r). This yields a relationship of the form:

[
Y = \alpha – \beta r
]

That negative coefficient of (r) is the key: higher interest rates reduce investment and therefore reduce output demanded, so IS slopes down in ((r, Y)) space.

How shifts in parameters move IS

Common exam shocks:

• Increase in (G) (fiscal expansion):
  • Directly increases planned spending → IS shifts right.
• Tax increase (T):
  • Reduces disposable income → lowers consumption → IS shifts left.
• Increase in autonomous consumption (a):
  • Higher consumption at each income level → IS shifts right.
• Increase in investment sensitivity (d) (or a change in investment demand):
  • Can change how strongly (r) affects (I), effectively changing the slope and possibly shift depending on how the underlying parameters change.

Explaining the equilibrium change

If IS shifts right:

1. At unchanged (r), higher spending increases (Y).
2. Higher (Y) increases money demand (since transactions rise).
3. Money market pushes (r) upward until equilibrium returns.

This produces the typical IS–LM comparative statics:

• (Y) increases
• (r) increases
• Investment can be partially crowded out

The magnitude depends on slopes: how steep IS is and how steep LM is (which depend on (b), (d), and money-demand parameters).

The money market: deriving and interpreting LM

Real money balances and money demand

LM is typically derived from:

[
\frac{M}{P} = L(Y, r)
]

• (M): nominal money supply (set by central bank)
• (P): price level (often taken as fixed within the short-run IS–LM framework)
• (L(Y,r)): real money demand increases with (Y) and decreases with (r)

A standard functional form could be:

[
L(Y,r) = kY – hr
]

Then equilibrium yields:

[
\frac{M}{P} = kY – hr
]

Solve for (r):

[
r = \frac{k}{h}Y – \frac{1}{h}\frac{M}{P}
]

This implies LM is upward sloping in ((r,Y)): at higher output, interest rates must rise to reduce money demand.

Policy shift: monetary expansion

If central bank increases (M):

• (M/P) increases (real money balances higher)
• To restore money market equilibrium, (r) must fall at a given (Y), which corresponds to LM shifting right/down in the (r-Y) diagram conventions often used.

The common exam interpretation:

• (M \uparrow) → LM shifts right → (r \downarrow) → investment rises → (Y \uparrow)

Again, the result depends on LM slope: if money demand is very sensitive to interest rates, output changes more; if LM is steep, output responds less.

Combining IS and LM: predicting outcomes from shocks

Fiscal expansion (closed economy)

Consider an increase in (G):

1. IS shifts right.
2. Intersection with LM occurs at higher (Y) and higher (r).
3. Higher (r) reduces investment (crowding out), so output rise is less than it would be under fixed (r).

Exam-quality explanation:
Fiscal policy raises demand for goods; because money market requires interest rates adjust, financial conditions tighten partially; investment crowds out consumption/investment composition.

Monetary expansion (closed economy)

Consider an increase in (M):

1. LM shifts right.
2. New intersection at higher (Y) and lower (r).
3. Lower (r) boosts investment.

Exam-quality explanation:
Lower interest rates increase investment and stimulate output; rising output increases money demand, which gradually pushes (r) up again until equilibrium.

Liquidity trap and policy effectiveness (typical exam twist)

Some courses include the idea that when interest rates are very low, money demand becomes highly elastic—so LM becomes almost horizontal. In that case:

• Monetary policy becomes less effective (interest rate cannot fall much).
• Fiscal expansion may be more effective if IS intersects at higher output without forcing (r) upward substantially.

In exam answers, it’s enough to say:

• If LM is flatter (interest rate-insensitive), monetary expansion produces larger output effects.
• If LM is flat/horizontal, monetary policy may not shift interest rates, but could still raise output if money demand responds weakly to (r). Many variants exist depending on the model; align with your course notes.

AD–AS and linking output to inflation

IS–LM is usually short-run with a fixed price level (P). AD–AS extends to inflation and price adjustment.

Aggregate demand

In many macro courses:

• AD is downward sloping: higher price level reduces real money balances (M/P), increasing interest rates and lowering investment and output.
• Thus, AD can be interpreted as derived from IS–LM with price level changes affecting money market equilibrium.

Aggregate supply

AS can be:

• Short-run upward sloping due to sticky wages/prices: output deviates from natural level in response to demand shocks.
• Long-run vertical at potential/natural output: real variables revert once prices and wages fully adjust.

Interpreting common shocks

1. Demand shock (e.g., monetary expansion)
   • AD shifts right: output rises in short run, price level rises.
   • In long run, output returns to natural level; inflation absorbs the shock.
2. Supply shock (e.g., cost-push)
   • AS shifts left: output falls and price level rises (stagflation-like outcome).
   • Demand policy might stabilize output but could worsen inflation depending on AS dynamics.

Labour-market link: inflation, unemployment, and the output gap

Even if your exam doesn’t ask for a full Phillips curve derivation, you need to connect macro output to labour outcomes.

Natural rate and the output gap

A typical narrative:

• In the long run, output tends to its natural rate (Y^*).
• The output gap (Y – Y^*) affects inflation dynamics:
  • When output is above natural level, unemployment tends to fall and wage pressure increases → inflation rises.
  • When output is below natural, inflation pressure falls.

Phillips curve logic (short run vs long run)

A common structure:

• Short-run Phillips curve: inflation rises when unemployment is low (or output gap positive).
• Long-run: unemployment returns to natural rate; sustained inflation requires persistent demand conditions.

For exam answers, be crisp:

• Demand stimulus can reduce unemployment temporarily, but in the long run unemployment returns to natural rate while inflation adjusts.
• Supply shocks can raise inflation while unemployment rises, worsening the trade-off.

Consistency check: common multi-part exam question structure

Intermediate macro exams often ask a sequence like:

1. “Increase in (G)”
2. “Describe effects on (Y), (r)”
3. “Now link to inflation in AS–AD”
4. “Discuss implications for unemployment”

A high-scoring answer uses the chain:

• Fiscal expansion → IS right → (Y\uparrow), (r\uparrow) (crowding out)
• Higher (Y) relative to natural → output gap positive → inflation rises
• In labour market, unemployment falls short run then returns, with inflation elevated in long run

ECO2004S: Open-Economy Macroeconomics—Exchange Rates, Net Exports, Capital Flows, and Policy Regimes

South Africa’s macro environment makes open-economy thinking highly relevant: exchange rates influence import prices, inflation, and net exports. Intermediate macro exams often test whether you can explain how fiscal/monetary policy works under fixed vs flexible exchange rates and how capital flows respond to interest differentials.

Core open-economy concepts you must master

Exchange rate and net exports channel

The exchange rate (E) affects:

• Imports: if domestic currency depreciates (higher (E) depending on convention), imports become more expensive → imports fall (at least in volume terms).
• Exports: depreciation makes domestic goods cheaper to foreigners → exports rise.

Net exports (NX = X – M) typically increases when depreciation occurs (again depending on elasticity assumptions).

Balance of payments intuition

The balance of payments conceptually includes:

• Current account (trade balance plus income transfers)
• Capital account/financial flows (portfolio and direct investment)

In intermediate models, the key link often becomes:

• Interest rates relative to the world affect capital flows and thus the exchange rate under flexible regimes.

Money–interest parity and capital flows (model logic)

A common exam framework uses interest parity:

[
r \approx r^* + \text{expected change in exchange rate}
]

In many simplified intermediate treatments under perfect capital mobility:

• Domestic interest rate closely tracks the world interest rate (r^*) (adjusted for exchange rate expectations).
• If domestic policy tries to push (r) away from (r^*), capital flows pressure the exchange rate until parity holds.

Even if your course uses a specific name like UIP (Uncovered Interest Parity), the mechanism is what matters:

• High domestic interest attracts capital inflows → currency appreciates → net exports worsen (partly offsetting output gains).
• Low domestic interest leads to outflows → currency depreciates → net exports improve (supporting output).

IS–LM with open economy: exchange-rate and net export feedback

Many intermediate courses use an “IS–LM–BP” logic where:

• IS depends on net exports, which depend on the exchange rate.
• BP (balance of payments) depends on capital flows, which depend on interest rates and exchange rate expectations.

Because interest rates and exchange rates are linked through capital flows, policies may have different real effects depending on the exchange regime.

Policy under fixed exchange rates: why central bank loses independence (often)

Fixed exchange rate regime intuition

If the exchange rate is pegged:

• When market pressure would depreciate the currency, the central bank buys foreign currency (or sells domestic currency) to maintain the peg.
• Monetary policy is constrained because defending the peg determines the money supply endogenously.

Typical exam result: fiscal policy has larger output effects

With a fixed exchange rate and high capital mobility:

• Monetary policy may be ineffective (central bank adjusts to defend the peg).
• Fiscal policy can shift IS right, raising output and interest rates, but interest rate pressures are constrained by the peg’s requirements and capital flows.

Depending on the exact model specification, typical outcomes include:

• Fiscal expansion tends to increase output more under fixed rates than under flexible rates because exchange rate does not adjust freely.
• But foreign reserves/money supply dynamics may create offsetting effects.

If your course emphasizes monetary independence under flexible rates, then the standard narrative becomes:

• Fixed exchange rate → monetary policy constrained; fiscal is more powerful (until balance-of-payments limits bind).

Policy under flexible exchange rates: the exchange rate acts as shock absorber

Flexible exchange rate intuition

If the exchange rate floats:

• Monetary expansion lowers domestic interest rates relative to the world.
• Capital outflows occur → currency depreciates.
• Depreciation improves net exports → output rises further (or offset depending on magnitudes).

Thus, under flexible rates, monetary policy can have strong real effects through both:

1. IS–LM interest rate channel (lower (r) stimulates investment)
2. Exchange-rate channel (depreciation boosts net exports)

But depreciation can also worsen inflation via import prices, linking to AS/AD and inflation expectations.

Depreciation and inflation: a mechanism relevant to South African context

Exchange rate depreciation can raise the domestic price level through:

• Direct import price increases (consumer goods and intermediate inputs)
• Production costs for firms using imported inputs
• Second-round effects if workers and firms adjust wage/price expectations

In exams, you are rarely required to compute pass-through quantitatively unless the question supplies data. Instead, you need to clearly explain the transmission:

• Depreciation → higher (P) via import prices → real money balances fall → interest rates rise (in the short run) → output can be affected depending on model and timing.

Trade balance elasticities and the output effect of depreciation

A high-scoring answer acknowledges that the net export channel depends on responsiveness:

• If exports are inelastic, depreciation yields small improvement in (NX), so output response is weaker.
• If imports are inelastic, depreciation reduces imports less, again weakening the effect.

So, the real effect of depreciation depends on:

• Price elasticities of exports and imports
• Availability of substitutes
• Credit conditions and exchange-rate uncertainty

In exam essays, adding one sentence like “output response depends on trade elasticities” can separate excellent answers from average ones.

A common multi-part exam question and a complete response strategy

Consider a question:

• “Central bank increases money supply under a flexible exchange rate. What happens to (Y), (r), (E), and NX? What about inflation?”

A complete solution chain:

1. Money supply up → LM shifts right → (r\downarrow)
2. Lower (r) relative to world (r^*) → capital outflows → currency depreciates (exchange rate rises in most depreciation conventions)
3. Depreciation → exports up and imports down → NX increases
4. NX increase reinforces output: (Y\uparrow)
5. Depreciation also increases import prices → inflation up in the short run
6. If output exceeds natural level, inflation pressure rises further; in long run output returns but inflation stays higher unless policy changes

Make sure your final statements are consistent with your assumed model timing: short-run output effects with longer-run return to natural output.

ECO2004S: Inflation, Monetary Policy Frameworks, and the Labour Market—From the Output Gap to Unemployment and Expectations

Intermediate macro exams frequently test whether you can integrate inflation dynamics with policy decisions. In a South African setting, it’s common to connect monetary policy goals to inflation outcomes and to discuss how labour-market rigidities influence adjustment.

Price level versus inflation: keep definitions straight

• Price level (P) is the overall level of prices.
• Inflation is the rate of change in prices, often measured as:
  [
  \pi = \frac{P_t – P_{t-1}}{P_{t-1}}
  ]
  or as log differences depending on notation.

In many macro models:

• Short-run: changes in (P) affect real balances (M/P), and hence output and interest rates.
• Inflation dynamics: often depend on output gaps and expectations.

If your exam uses “inflation targeting” language, it’s essentially about controlling inflation (and indirectly output and employment stability) through monetary policy decisions.

The money growth / inflation connection (monetary neutrality idea)

A common intermediate macro viewpoint:

• In the long run, the money supply growth rate tends to affect the inflation rate because nominal variables must adjust.
• Real output is largely governed by real factors (technology, labour force growth, productivity, investment in human/physical capital).

So, a policy maker can stimulate real output temporarily when prices/wages are sticky, but in the long run inflation adjusts.

To score marks, state:

• short-run effects: aggregate demand and output can rise
• long-run effects: output returns to potential; inflation bears the adjustment

Monetary policy rules vs discretionary policy

Exams may ask: “How should the central bank respond to shocks?” Typical answers reference:

• Discretionary policy: respond to current conditions, potentially causing credibility problems.
• Rules-based policy: consistent response; increases credibility, anchoring expectations.

Even if your course doesn’t focus heavily on Taylor rules, a rule-like statement is useful:

• If inflation is above target, policy should be tighter (higher interest rates) to reduce inflation pressure.
• If inflation below target and output below potential, policy can be more accommodative.

Expectations: why inflation persistence happens

Many intermediate macro models include expectations. The key reasoning:

• If households and firms expect higher inflation, they adjust wages and prices accordingly.
• That means inflation can remain high even if demand conditions start improving.

Thus, policy effectiveness depends on credibility and expectation management.

In exam answers, it helps to distinguish:

• Demand shock: can shift output and inflation temporarily
• Inflation expectations shift: can change inflation persistence more permanently unless policy credibility restores anchored expectations

The labour market: unemployment, wage setting, and Phillips curve

Unemployment and wage rigidity

In many real-world settings (including South Africa), wages are not perfectly flexible:

• Wage bargaining, minimum wages (if applicable in your course context), contracts, and adjustment costs create stickiness.
• As a result, unemployment adjusts more slowly and inflation-unemployment trade-offs may persist.

Output gap and inflation

A typical Phillips-curve-like relationship:

• Inflation depends negatively on unemployment (or positively on the output gap).
• When output is above potential, unemployment falls and inflation rises.
• When output falls below potential, unemployment rises and inflation falls.

If asked “what happens to unemployment when monetary policy is expansionary?”:

• Short run: unemployment can fall.
• Long run: unemployment tends back toward natural rate; inflation increases if policy keeps demand above potential persistently.

Supply shocks and the breakdown of the easy trade-off

A demand stimulus is not equally effective under supply shocks.

If costs rise (e.g., energy/input prices), AS shifts left:

• Output falls
• Inflation rises

In this situation:

• Attempting to offset output falls with tighter monetary policy could reduce inflation but increase unemployment further.
• Attempting to reduce unemployment with expansionary policy could worsen inflation further.

Intermediate macro exams like to test that you can articulate the policy dilemma under supply shocks.

Linking open economy and inflation to labour markets

Open-economy depreciation affects inflation via import prices. Then labour markets respond through wage bargaining:

• Higher import prices raise cost of living → workers seek higher nominal wages.
• Firms pass some costs to prices → inflation becomes persistent.

Thus, in an open economy, exchange rate movements can influence both inflation and labour outcomes.

Even if your question is “closed economy,” examiners sometimes accept an “extension” paragraph using open-economy reasoning if it’s logically relevant.

A structured response to a complex exam scenario

Imagine a question like:

• “Suppose inflation rises above target and output is above potential. Explain how the central bank should respond and what happens to unemployment in the short run and long run.”

A strong response structure:

1. Identify the shock and conditions
   • Inflation above target; output above potential → demand pressure is likely strong and unemployment is likely below natural rate.
2. Monetary policy action
   • Tighten policy: raise interest rates to reduce aggregate demand (shift AD left / LM left or restrain money growth).
3. Short-run labour effect
   • Output falls toward potential → unemployment rises (moves upward toward natural rate).
4. Short-run inflation effect
   • Inflation starts to fall because demand pressure eases; however, inflation may fall gradually depending on expectations.
5. Long-run outcome
   • Unemployment returns to natural rate; inflation returns to target if expectations are anchored and policy credibility is maintained.

This kind of “chain” is exactly what intermediate macro exams want.

ECO2004S: Practice-Ready Calculations, Comparative Statics, and Exam-Winning Problem-Solving

This final section is designed to be “mechanically useful.” It provides step-by-step solution patterns for the most common quantitative tasks: solving IS–LM-like systems, interpreting comparative statics, connecting policy changes to equilibrium shifts, and handling open-economy extensions. It also includes South Africa-relevant framing for inflation and external shocks.

Quantitative skill 1: Solving a simple IS–LM system (template)

A frequent exam problem provides a linearized system like:

• IS: (Y = c – m r)
• LM: (r = \ell Y – n \frac{M}{P})

You’re asked to find equilibrium (Y) and (r), then analyze what happens when (G) or (M) changes.

Step-by-step procedure

1. Write the equilibrium condition
   • Set the expressions for (r) equal or substitute one equation into the other.
2. Solve for (Y)
   • Substitute (r) in IS using LM’s expression, or vice versa.
3. Back-substitute to find (r)
   • Use the solved (Y) in LM (or IS).
4. Do comparative statics
   • Compute derivative sign: e.g., if (G) increases, does (Y) increase? Does (r) increase?
5. Interpret economically
   • Give a one-to-two sentence interpretation referencing crowding out or investment channel.

Comparative statics without heavy algebra (exam-friendly)

If the problem is symbolic and you don’t have time for full algebra, you can still score by stating:

• A shift right in IS increases intersection (Y).
• Because LM is upward sloping, (r) rises too.
• Then interpret with investment dependence on interest rates.

The key is to ensure your diagram directions match your algebra signs.

Quantitative skill 2: Interpreting slope effects (why magnitude differs)

Exams may ask:

• “Why is monetary policy more effective when LM is flatter?”
• “Why do output responses depend on the interest sensitivity of investment?”

The logic:

• If investment is highly sensitive to (r) (large (d)), then a small interest rate change causes a large investment change → larger (Y) response.
• If money demand is highly sensitive to (r) (large (h)), LM is flatter, and monetary policy shifts can cause larger (r) changes and output response depending on model form.

To score:

• Don’t just say “it depends.”
• State the channel: either “investment channel” or “money demand channel.”

Quantitative skill 3: AS–AD mapping from demand shocks

Even without full numeric computations, you often need to connect:

• a demand shift (AD right)
  to:
• short-run output up, inflation up
  and then:
• long-run output returns to potential.

A frequent exam trap is to keep (Y) permanently higher after an AD shock. The AS–AD model with a vertical long-run AS at (Y^*) implies:

• Long run: (Y) returns to (Y^*).
• Short run: output rises, but price level adjusts until the output gap closes.

Quantitative skill 4: Labour-market outcomes from output gaps

If asked:

• “How does an increase in demand affect unemployment over time?”

Use this staging:

1. Short run: unemployment falls as output rises above potential.
2. Adjustment: wages/prices respond; unemployment drifts back.
3. Long run: unemployment returns to natural rate.

If exam expects unemployment to rise when demand is reduced, state:

• contraction increases unemployment in short run; long run returns.

Open economy quantitative thinking: consistent sign logic

Often open-economy exams are “sign-based” rather than numeric:

• Under flexible exchange rates, a monetary expansion lowers interest rates → depreciation → improved net exports → output up.
• Under fixed rates, interest rates may not change (or money supply adjusts to maintain the peg), altering the output effect.

If a question gives multiple scenarios, present them systematically:

Scenario grid (what to check)

Policy	Exchange rate regime	Expected movement in (E)	Expected movement in (NX)	Main output effect
Money supply increases	Flexible	Depreciation (currency weakens)	(NX\uparrow)	Output tends to rise
Money supply increases	Fixed	Peg holds (E)	(NX) ambiguous (depends on other channels)	Output effect weaker/indirect
Fiscal expansion	Flexible	Appreciation (if (r\uparity) rises)	(NX\downarrow)	Output rise partially offset
Fiscal expansion	Fixed	Peg holds (E)	(NX) less affected	Output rise stronger

This table is a sign logic map you can adapt.

Worked example style (structured narrative with placeholders)

Because intermediate macro exams often use linear relations, you can write your solution in a consistent format even if numeric values differ.

Example template: fiscal expansion under IS–LM

1. State equations:
   • (Y = a + b(Y-T) + \bar{I} – dr + G)
   • Money market: (M/P = kY – hr)
2. Solve:
   • Derive IS: (Y = \alpha – \beta r)
   • Derive LM: (r = \gamma Y – \delta (M/P))
3. Set intersection:
   • Substitute (r) from LM into IS to solve (Y)
4. Compare with baseline:
   • Increase in (G) increases IS intercept → (Y\uparrow) and (r\uparrow)
5. Interpret:
   • Output rise supports consumption; higher (r) reduces investment; crowding out partial.

Even when the exam expects short answers, the structure earns method marks.

Case-style reasoning grounded in South African macro themes

Case A: Inflation increases due to exchange-rate depreciation

Exam question may ask:

• “Explain the transmission from depreciation to inflation and then to policy response.”

Use this chain:

1. Depreciation raises import prices.
2. Higher import prices raise domestic costs for firms and the consumer price index.
3. Workers demand higher nominal wages; firms adjust prices → inflation persistence.
4. Central bank tightens monetary conditions to reduce aggregate demand and bring inflation toward target.
5. Output slows; unemployment rises toward natural rate in the short run; in long run inflation stabilizes.

Case B: Demand shock expansionary policy during weak labour market conditions

If unemployment is high and output below potential:

1. Expansionary monetary or fiscal policy shifts demand right.
2. Output rises; unemployment falls short run.
3. If demand remains too strong, inflation rises; central bank may reverse to avoid overshooting target.
4. Labour market returns to natural rate; inflation absorbs the policy-driven adjustment.

This kind of reasoning is a strong essay foundation because it integrates all three: demand, inflation, unemployment.

Exam strategy: how to allocate time and avoid errors

Before you answer: read for the model type

Ask yourself:

• Is the question about output and interest rates? → likely IS–LM.
• Is it about price level and output? → likely AS–AD.
• Is it about exchange rates and trade? → open-economy regime.
• Is it about inflation persistence and unemployment? → expectations and Phillips curve logic.

During calculations: keep symbolic clarity

• Use consistent notation for parameters (e.g., (a,b,T,\bar{I},d,k,h)).
• Keep sign conventions consistent.

If the exam provides specific equations, don’t switch forms mid-solution.

A final “mark-maximising” checklist for ECO2004S-style problems

When finishing an answer, check:

• Did you identify the correct model(s)?
• Did you state whether variables rise or fall and why?
• Did you connect short run to long run where appropriate?
• Did you include a diagram description when a diagram is likely needed?
• Did you avoid common pitfalls (like long-run output staying shifted by a demand shock)?
• Did you keep your reasoning internally consistent (signs, mechanisms, and directions)?

Consistency is where many marks come from—examiners grade the coherence of your model-based explanation.

If you want, I can also generate a full set of mock exam questions (with marking rubrics) specifically aligned to the topics above: IS–LM derivations, AS–AD shock analysis, Phillips curve/output gap essays, and open-economy policy regime comparisons, with solutions in the same “template + mechanism + diagram logic” style.