How to Answer 4-Mark Questions in IB Economics

Students often lose easy marks in IB Economics because they treat 4-mark questions like mini essays. A 4-mark response does not need a long introduction. It needs a tight economic chain.

The formula for most 4-mark answers

Cause → Shift → Price → Quantity → Case link

That structure works across tariffs, exchange rates, subsidies, and demand or supply shocks.

Example

Improved roads reduce transport costs

• Lower costs increase supply
• The supply curve shifts right
• Equilibrium price falls
• Equilibrium quantity rises
• The case-study good becomes cheaper in local markets

What examiners want to see

• A relevant diagram if the question requires one
• Correct shift direction
• One clear explanation of the new equilibrium
• A sentence anchored to the case study

For a good model, compare this structure against the Kenya walkthrough and the Bhutan walkthrough.

Common mistakes

• No diagram when the question clearly invites one
• Writing theory with no final price or quantity effect
• Ignoring the case-study context completely
• Explaining the wrong curve shift