What is the AD-AS model in Macroeconomics?

The AD-AS model, or Aggregate Demand-Aggregate Supply model, is a fundamental framework in Macroeconomics used to explain price levels and output through the relationship between aggregate demand (AD) and aggregate supply (AS). It helps in understanding economic fluctuations and the impact of fiscal and monetary policies. In the IB DP Economics curriculum, this model is crucial for analyzing how different factors affect the overall economy.

How does a shift in Aggregate Demand (AD) affect the economy?

A shift in Aggregate Demand (AD) can significantly impact the economy. An increase in AD, often due to factors like increased consumer spending or government expenditure, can lead to higher output and price levels, potentially causing inflation. Conversely, a decrease in AD might result in lower output and deflationary pressures. Understanding these shifts is essential for IB DP students to analyze economic policies and their effects on growth and stability.

What causes shifts in Aggregate Supply (AS) in the AD-AS model?

Shifts in Aggregate Supply (AS) can be caused by changes in factors such as resource availability, technological advancements, and production costs. For instance, an improvement in technology can increase AS, leading to higher output and lower prices. Conversely, an increase in production costs, like wages or raw materials, can decrease AS, resulting in higher prices and lower output. These shifts are crucial for IB DP Economics students to understand economic dynamics and policy implications.

How do fiscal and monetary policies influence the AD-AS model?

Fiscal and monetary policies play a significant role in influencing the AD-AS model. Fiscal policy, through government spending and taxation, can directly affect Aggregate Demand. For example, increased government spending can boost AD, leading to higher output and prices. Monetary policy, through interest rates and money supply, also impacts AD by influencing consumer and business spending. Understanding these policies is vital for IB DP students to evaluate their effectiveness in achieving economic objectives.

What is the significance of the long-run Aggregate Supply (LRAS) curve in the AD-AS model?

The long-run Aggregate Supply (LRAS) curve represents the economy's maximum sustainable output level, assuming full employment and efficient resource use. It is vertical, indicating that in the long run, output is determined by factors like technology and resources, not price levels. For IB DP Economics students, the LRAS curve is essential for understanding potential economic growth and the limitations of demand-side policies in affecting long-term output.

Why is "Treating AD-AS as the same as micro demand-supply." a common mistake in AD - AS?

Why it happens: Same diagram shape. How to avoid it: Micro D-S: ONE market. AD-AS: WHOLE economy. Y-axis is price LEVEL (general); X-axis is real GDP (output).

Why is "Drawing LRAS as upward-sloping." a common mistake in AD - AS?

Why it happens: Confusing with SRAS. How to avoid it: LRAS is VERTICAL at potential output — price level doesn't change real output in the long run.

AD-AS model

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Aggregate Demand and Aggregate Supply (AD-AS) — IB Economics SL: components, shifts, SRAS vs LRAS

Unit 3.2 of the 2022+ syllabus. The AD-AS model — economy-wide demand and supply at the aggregate price level. Drives growth, unemployment, and inflation analysis.

At a glance

AGGREGATE DEMAND (AD): total spending on a country's goods and services at each price level.
AD = C + I + G + (X − M).
AD slopes DOWN (wealth effect, interest rate effect, exchange rate effect).
AD SHIFTERS: anything that changes C, I, G, or X−M (taxes, confidence, interest rates, exchange rates, world income).
AGGREGATE SUPPLY (AS): total output supplied at each price level.
SRAS slopes UP (sticky wages and prices).
LRAS is VERTICAL at potential output (full-employment level).
Equilibrium: AD = AS determines price level and real GDP.

What you’ll learn

Mapped to the IB DP Economics SL subject guide (2022 onwards (first assessment May 2024)).

3.2.1 — Define and identify components of AD.
3.2.2 — Distinguish SRAS and LRAS.
3.2.3 — Identify shifters of AD and AS.

Aggregate Demand

Total spending on the economy.

Aggregate Demand (AD) = total spending on domestically produced goods and services at each price level, in a given period.

$AD = C + I + G + (X - M)$

where:

C = consumer spending (largest component, typically 60-70% of GDP).

Aggregate Supply (SRAS and LRAS)

Short run vs long run.

Short-run aggregate supply (SRAS). Total output firms produce at each price level when input prices (especially wages) are fixed.

SRAS slopes UP because:

Sticky wages: firms can sell more at higher prices while wages are still based on old contracts → more profitable to expand.
Some firms have spare capacity.
Sticky/menu-cost pricing.

Shifters of SRAS (anything changing input costs):

Wages.
Raw material prices (oil, materials).
Indirect taxes / subsidies on producers.
Exchange rate (affects imported inputs).
Supply shocks (e.g. natural disasters).

Long-run aggregate supply (LRAS). Output at FULL EMPLOYMENT — the economy's potential output (Yf). In the long run, all prices and wages adjust, so output is determined by REAL factors:

Quantity and quality of labour.
Capital stock.
Technology.
Natural resources.

LRAS is VERTICAL at the full-employment level — the price level doesn't determine real output in the long run.

Shifters of LRAS:

Increased labour force (immigration, participation).
Higher labour productivity (education, training, technology).
Investment in capital.
Discovery of resources.
Better institutions, infrastructure.

LRAS shifting RIGHT = potential growth (PPC also shifts right).

Quick recap

AD = C + I + G + (X−M); slopes down.
SRAS up, LRAS vertical at Yf.
AD shifters: C, I, G, X−M determinants.
SRAS shifters: input costs.
LRAS shifters: real factors.

Memorise this

Verbatim phrases, formulae and definitions IB DP mark schemes credit (key for AO1 knowledge marks on Paper 1).

AD = C + I + G + (X − M)
AD slopes down: wealth, interest, trade effects
SRAS slopes up: sticky wages
LRAS vertical at Yf
LRAS shifters: labour, capital, tech

How it’s examined

Paper 1: 'Using a diagram, explain the impact of a fall in business confidence on AD.' Paper 2: identify direction of AD or AS shifts from data response.

Sources: IB Diploma Programme Economics subject guide (IBO, 2020 — first assessment 2022). Last reviewed 2026-05-31.

Component	Shifters
C	Consumer confidence, income tax, household wealth, interest rates
I	Business confidence, interest rates, corporation tax, technological change
G	Government policy decisions
X − M	Exchange rate, world income, trade barriers, domestic competitiveness

AD - AS – Study Notes & Past Paper Style Questions | IB Economics SL | Tutopiya

AD - AS

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AD - AS — frequently asked questions

Aggregate Demand and Aggregate Supply (AD-AS) — IB Economics SL: components, shifts, SRAS vs LRAS

At a glance

What you’ll learn

Aggregate Demand

Aggregate Supply (SRAS and LRAS)

Quick recap

Memorise this

How it’s examined

Step-by-step worked examples — AD - AS

1Business confidence falls

2Oil price shock

3What shifts LRAS?

Key Definitions and Keywords — AD - AS

Aggregate Demand

Short-run aggregate supply

Long-run aggregate supply

Common Mistakes and Misconceptions — AD - AS

✕Treating AD-AS as the same as micro demand-supply.

✕Drawing LRAS as upward-sloping.