4.6 Price Stability

Cambridge International AS Level Economics (9708)


2026 📋 Syllabus Objectives

By the end of these notes, you should be able to:

  1. Define inflation, deflation, and disinflation
  2. Explain how changes in the price level are measured using the Consumer Price Index (CPI), and identify possible difficulties in measuring it
  3. Distinguish between money (nominal) values and real data
  4. Explain the causes of inflation: cost-push and demand-pull
  5. Explain the consequences of inflation

1. Definitions: Inflation, Deflation, and Disinflation

🔺 What is Inflation?

Inflation is a sustained (ongoing) increase in the general price level of an economy over a period of time.

A few important things to note:

  • The word sustained means prices are rising over time, not just once.
  • General price level means the average of all prices in the economy — not just one product.
  • If only the price of one good rises (say, tomatoes become more expensive), that is not inflation.

Example: If a basket of common goods costs USD 100 in January and USD 107 in December of the same year, the economy has experienced 7% inflation.

Types of inflation by severity:

TypeRateWhat it means
Creeping inflation1–5% (ideally 2–3%)Low, manageable inflation — generally considered healthy
Running inflationDouble-digit (e.g. 10%+)Higher and more damaging to the economy
Hyperinflation100% or moreExtreme inflation where money almost loses its value entirely

⚠️ Three Key Points Students Often Get Wrong

Point 1: If inflation is at a constant rate (e.g. 3% every year), prices are NOT staying the same — they are still rising, just at a steady pace.

Point 2: During disinflation (when inflation is falling, e.g. from 7% to 2%), prices are NOT falling — they are still going up, just more slowly than before.

Point 3: Prices only actually fall when the inflation rate becomes negative — that is called deflation.


🔻 What is Deflation?

Deflation is when the general price level decreases over time — in other words, the inflation rate becomes negative.

Example: If the inflation rate is −2%, prices across the economy are falling by 2%.

Deflation is not always a good thing. There are two types:

Good DeflationBad Deflation
Caused by an increase in aggregate supply (more production capacity)Caused by a decrease in aggregate demand (people spending less)
Prices fall while output and productivity riseSpending falls → firms earn less → they hire fewer workers → unemployment rises
Rare; associated with technological progressCan trigger a recession (fall in national output)
Supply-side policies can cause thisGovernment tries to fix it with lower taxes or lower interest rates

Simple Example of Bad Deflation: During an economic crisis, people panic and stop spending. Shops can't sell their goods, so they cut prices to attract buyers. Firms make less profit, lay off workers, and the cycle worsens.

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