How to Write a 10-Mark Economics Answer — IB Economics HL

① Define key terms

Common access resources (also called common pool resources) are resources that are rivalrous — one person's use reduces availability for others — but non-excludable, meaning no one can be prevented from using them. Examples include ocean fish stocks, forests, and clean air.

② Define the second key term

Market failure occurs when the free market fails to allocate resources efficiently, resulting in a loss of economic welfare. In this case, the market failure arises because common access resources have no defined ownership and therefore no price mechanism to signal scarcity.

③ Explain the incentive problem

Because there is no owner to charge a price, individual users have an incentive to maximise their own consumption. A fishing company will continue to increase its catch because the private marginal cost (MPC) of fishing does not include the cost imposed on other fishers or on the ecosystem.

④ Identify the externality

This creates a negative externality of production: the marginal social cost (MSC) of extracting the resource exceeds the MPC. The difference between MSC and MPC is the external cost — the damage to the ecosystem and to other users that the individual firm does not pay for.

⑤ Introduce and explain the diagram

This can be shown on the diagram below. The market produces at Q_m where MPC = MSB (demand), because firms only consider their private costs. However, the socially optimal output is Q_opt where MSC = MSB.

⑥ Explain the welfare loss

The resource is overconsumed by Q_m − Q_opt. For every unit between Q_opt and Q_m, the MSC exceeds the MSB. The shaded triangle represents the deadweight loss (DWL).

⑦ Real-world example

A clear example is overfishing in the North Atlantic. Cod populations in the Grand Banks collapsed to less than 1% of historical levels by the 1990s because no single entity bore the full social cost of extraction.

⑧ Explain the tragedy of the commons

This is the tragedy of the commons: each user acts rationally in self-interest, but collectively the resource is degraded or depleted.

⑨ Conclude

Therefore, common access resources lead to market failure because the absence of ownership creates a divergence between private costs and social costs, resulting in allocative inefficiency. Without government intervention (quotas, tradable permits, taxation), the resource will continue to be overused.

① State the recommendation

I recommend that the Japanese government implements expansionary fiscal policy, specifically increased government spending on infrastructure and green energy projects, to boost aggregate demand and push inflation toward the 2% target.

② Explain how the policy works

Expansionary fiscal policy involves increasing government expenditure or cutting taxes to stimulate economic activity. When the government increases spending, this directly raises a component of aggregate demand (AD = C + I + G + X − M). The resulting rightward shift in AD increases both real GDP and the general price level — moving the economy toward the 2% inflation target.

③ Explain the multiplier effect

Moreover, government spending has a multiplier effect: each yen spent creates income for workers and suppliers, who then spend a portion of that income, generating further rounds of spending. This amplifies the initial fiscal injection.

④ Reference the text/data — why monetary policy has failed

The text states that the Bank of Japan's interest rate has been at −0.1% since 2016, yet inflation remains below target. This suggests monetary policy has been ineffective — Japan appears to be in a liquidity trap where further interest rate reductions cannot stimulate spending. Additionally, with consumer spending weak despite 2.6% unemployment and household savings rising to 8.4%, there is a confidence problem that direct government spending can address more effectively than further monetary easing.

⑤ Evaluate — limitations

However, there are significant limitations. Japan's government debt is already 263% of GDP — the highest among developed economies. Further fiscal expansion increases the debt burden and may crowd out private investment if interest rates eventually rise. There is also the risk of wasteful allocation if spending is not directed toward productive investments.

⑥ Justified conclusion

On balance, given the failure of ultra-loose monetary policy over more than two decades and the weak consumer spending, expansionary fiscal policy targeted at productivity-enhancing infrastructure is the most appropriate recommendation. The high debt level is a concern, but the cost of continued deflation — falling real wages, delayed consumption, and rising real debt burdens — is arguably greater.