2023 IB DP Economics 模擬試題連答案詳解

An outstanding response will include the following:

1. **Definitions**:
- **Infant Industry**: A newly established domestic industry that has a potential comparative advantage but is currently unable to compete with established foreign competitors due to a lack of economies of scale.
- **Tariff**: A tax placed on imported goods.

2. **Economic Theory & Mechanism**:
- Newly established firms face high initial average costs (due to lack of experience, infrastructure, and small scale of production).
- Established international competitors operate with lower average costs due to significant economies of scale.
- Free trade would result in the domestic market being flooded with cheaper imports at the world price \(P_w\), driving the infant domestic firms out of business before they can mature.
- By imposing a tariff \(t\), the price of imported goods rises to \(P_w + t\).
- This tariff acts as a protective barrier, reducing the volume of imports and increasing the domestic price, which allows domestic infant firms to expand their output.
- Over time, as domestic production increases, the firms benefit from 'learning-by-doing', infrastructure improvements, and internal/external economies of scale. This shifts their average cost curve downward.
- Once the domestic firms are able to produce at a low enough average cost to compete internationally, the tariff can be removed, and the industry can survive under free trade.

3. **Diagram**:
- A standard international trade diagram showing domestic demand (D) and domestic supply (S).
- A horizontal world supply line at the world price \(P_w\), showing the initial quantity of domestic production \(Q_1\), total domestic consumption \(Q_4\), and imports \(Q_1\) to \(Q_4\).
- A new, higher horizontal line representing world supply plus the tariff at \(P_w + t\).
- This shows domestic production expanding to \(Q_2\), domestic consumption falling to \(Q_3\), and imports shrinking to the range between \(Q_2\) and \(Q_3\).
- Government tariff revenue is represented by the rectangle defined by the tariff rate times the new level of imports: \(t \times (Q_3 - Q_2)\).

Marks are allocated according to the IB Diploma Programme Economics Paper 1 Markbands for 10-mark questions:

- **9–10 marks**: The response demonstrates a highly precise and detailed understanding of the infant industry argument and the mechanics of a tariff. An accurate, fully labeled tariff diagram is provided, and it is explicitly integrated into the explanation to show how domestic production increases from \(Q_1\) to \(Q_2\) and imports decrease. Relevant economic terms are defined and used correctly throughout.
- **7–8 marks**: The response shows a good understanding of the infant industry argument and how tariffs work. A diagram is included and is mostly correct, though there may be minor labeling or explanation omissions. Key terms are defined correctly.
- **5–6 marks**: The response provides a basic description of the infant industry argument or a tariff, but the link between the two is weak. The diagram is either missing, poorly drawn, or not explained in relation to the infant industry context.
- **3–4 marks**: The response shows limited understanding, focusing descriptively on protectionism or tariffs without clearly demonstrating how the infant industry benefits. The diagram is highly flawed or absent.
- **1–2 marks**: The response is largely irrelevant, showing minimal understanding of the concepts of tariffs or infant industries.

An outstanding response will include the following:

1. **Definitions**:
- **Infant Industry**: A newly established domestic industry that has a potential comparative advantage but is currently unable to compete with established foreign competitors due to a lack of economies of scale.
- **Tariff**: A tax placed on imported goods.

2. **Economic Theory & Mechanism**:
- Newly established firms face high initial average costs (due to lack of experience, infrastructure, and small scale of production).
- Established international competitors operate with lower average costs due to significant economies of scale.
- Free trade would result in the domestic market being flooded with cheaper imports at the world price \(P_w\), driving the infant domestic firms out of business before they can mature.
- By imposing a tariff \(t\), the price of imported goods rises to \(P_w + t\).
- This tariff acts as a protective barrier, reducing the volume of imports and increasing the domestic price, which allows domestic infant firms to expand their output.
- Over time, as domestic production increases, the firms benefit from 'learning-by-doing', infrastructure improvements, and internal/external economies of scale. This shifts their average cost curve downward.
- Once the domestic firms are able to produce at a low enough average cost to compete internationally, the tariff can be removed, and the industry can survive under free trade.

3. **Diagram**:
- A standard international trade diagram showing domestic demand (D) and domestic supply (S).
- A horizontal world supply line at the world price \(P_w\), showing the initial quantity of domestic production \(Q_1\), total domestic consumption \(Q_4\), and imports \(Q_1\) to \(Q_4\).
- A new, higher horizontal line representing world supply plus the tariff at \(P_w + t\).
- This shows domestic production expanding to \(Q_2\), domestic consumption falling to \(Q_3\), and imports shrinking to the range between \(Q_2\) and \(Q_3\).
- Government tariff revenue is represented by the rectangle defined by the tariff rate times the new level of imports: \(t \times (Q_3 - Q_2)\).

Marks are allocated according to the IB Diploma Programme Economics Paper 1 Markbands for 10-mark questions:

- **9–10 marks**: The response demonstrates a highly precise and detailed understanding of the infant industry argument and the mechanics of a tariff. An accurate, fully labeled tariff diagram is provided, and it is explicitly integrated into the explanation to show how domestic production increases from \(Q_1\) to \(Q_2\) and imports decrease. Relevant economic terms are defined and used correctly throughout.
- **7–8 marks**: The response shows a good understanding of the infant industry argument and how tariffs work. A diagram is included and is mostly correct, though there may be minor labeling or explanation omissions. Key terms are defined correctly.
- **5–6 marks**: The response provides a basic description of the infant industry argument or a tariff, but the link between the two is weak. The diagram is either missing, poorly drawn, or not explained in relation to the infant industry context.
- **3–4 marks**: The response shows limited understanding, focusing descriptively on protectionism or tariffs without clearly demonstrating how the infant industry benefits. The diagram is highly flawed or absent.
- **1–2 marks**: The response is largely irrelevant, showing minimal understanding of the concepts of tariffs or infant industries.

An infant industry is a new domestic industry that has not yet established sufficient scale to compete with mature foreign competitors. The infant industry argument suggests that temporary trade protection allows these firms to grow, achieve economies of scale, and eventually compete internationally.

Arguments for Tariffs:
1. Price Protection: A tariff shifts the domestic supply curve of imports upward. The domestic price rises from the world price \(P_w\) to the tariff price \(P_w + t\). This increases domestic production from \(Q_1\) to \(Q_2\), allowing infant firms to capture market share and gain experience.
2. Government Revenue: Unlike subsidies, tariffs generate tax revenue for the government (equal to the area of the tariff rectangle: imports times the tariff rate), which can be reinvested in national infrastructure or education to further support the industry.

Arguments against Tariffs / Limitations:
1. Welfare Loss: Tariffs create deadweight loss (welfare loss of domestic overproduction inefficiency and consumer underconsumption). Consumers suffer from higher prices and lower consumer surplus.
2. Lack of Incentive to Innovate: Protection can breed dependency. Without competitive pressure, infant industries may fail to become efficient, leading to permanent protectionism (rent-seeking behavior).
3. Retaliation: Trading partners might retaliate with their own tariffs, hurting other domestic export-oriented sectors.

Alternative Policies:
1. Production Subsidies: Direct subsidies to domestic producers shift the domestic supply curve to the right. This allows domestic firms to expand output to \(Q_2\) without increasing the price for consumers (which remains at \(P_w\)). Thus, there is no consumption-side deadweight loss. However, this imposes a direct opportunity cost on the government's budget.
2. Supply-Side Investments: Improving education, vocational training, and infrastructure may more directly address the root causes of the infant industry's high costs without distorting international trade.

Evaluation & Synthesis:
While tariffs are politically appealing because they generate revenue rather than requiring government expenditure, they are rarely the 'most effective' policy in economic terms. Production subsidies are more targeted and avoid distorting consumer choice and causing consumption deadweight loss. Ultimately, any protectionist policy must be strictly time-bound to prevent permanent inefficiency, and must be accompanied by competitive disciplines to ensure the industry eventually matures.

Marks 1–3: Descriptors show little understanding of the prompt. Definitions of tariffs or protectionism are missing or incorrect.
Marks 4–6: Identifies and defines key terms. Suggests why protection might be needed but without clear link to infant industries. Diagram is missing or poorly drawn.
Marks 7–9: Explains how tariffs protect infant industries with an accurate tariff diagram. Compares domestic production before and after the tariff. Explains at least one limitation (e.g., deadweight loss).
Marks 10–12: Provides a clear, detailed analysis of tariffs and at least one alternative policy (most likely production subsidies) with supporting diagrams. Discussion covers impacts on different stakeholders (consumers, producers, government).
Marks 13–15: Evaluates the claim in a balanced and synthesized manner. Directly addresses 'most effective' by comparing the welfare implications of tariffs versus subsidies. Offers a clear, reasoned conclusion on the conditions under which these policies succeed or fail.

Depreciation refers to a decrease in the value of a currency relative to another currency. This occurs within a floating exchange rate system where the value is determined by the market forces of demand and supply.

Award [1] for identifying that it is a decrease in the value of a currency. Award [1] for specifying that this occurs due to market forces or in a floating exchange rate system.

Sustainable development is defined as development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Award [1] for mentioning meeting the needs of the present generation. Award [1] for mentioning not compromising the ability of future generations to meet their own needs.

First, calculate the percentage change in quantity demanded: \(\frac{3,500 - 5,000}{5,000} \times 100 = -30\%\). Second, calculate the percentage change in price: \(\frac{3.60 - 3.00}{3.00} \times 100 = 20\%\). Finally, apply the PED formula: \(\text{PED} = \frac{\% \Delta Q_d}{\% \Delta P} = \frac{-30\%}{20\%} = -1.5\). (Note: The absolute value of 1.5 is also acceptable).

1 mark for showing correct working (calculating the percentage change in quantity demanded as -30% and percentage change in price as 20%, or setting up the full formula correctly). 1 mark for the correct final answer of -1.5 (or 1.5).

The value of the USD has increased from 1.25 CAD to 1.40 CAD. Calculate the percentage change: \(\frac{1.40 - 1.25}{1.25} \times 100 = \frac{0.15}{1.25} \times 100 = 12\%\). Since the USD now buys more CAD, it has appreciated by 12%.

1 mark for showing correct working (the percentage change formula with correct values). 1 mark for the correct final answer of 12% appreciation (must state appreciation or positive change).

Apply the inflation rate formula: \(\text{Inflation Rate} = \frac{\text{CPI}_{\text{Year 2}} - \text{CPI}_{\text{Year 1}}}{\text{CPI}_{\text{Year 1}}} \times 100\). Substituting the numbers: \(\frac{108.9 - 104.2}{104.2} \times 100 = \frac{4.7}{104.2} \times 100 \approx 4.51\%\).

1 mark for showing correct working (setting up the formula with correct values). 1 mark for the correct final answer of 4.51% (accept 4.5% or 4.51%).

In the case of single-use plastics, consumers only consider their private benefits (MPB) and private costs (MPC) when making purchasing decisions, resulting in a market equilibrium where MPB = MPC at quantity \(Q_m\). However, the consumption of plastic creates negative externalities (such as environmental pollution and waste disposal costs) borne by third parties. This means the marginal social benefit (MSB) is less than the marginal private benefit (MPB). The socially optimal level of consumption is at \(Q_{opt}\), where MSB = MSC (assuming MSC = MPC). Because the free market level of consumption exceeds the socially optimal level (\(Q_m > \beta Q_{opt}\)), there is an overallocation of resources to this product. This creates a welfare loss to society, represented by the shaded deadweight loss triangle, signaling market failure.

Diagram (2 marks): 1 mark for a correctly labeled negative consumption externality diagram showing MPB, MSB, and MPC curves with MSB to the left of MPB. 1 mark for showing market equilibrium (Qm), social optimum (Qopt), and the shaded area of welfare loss. Explanation (2 marks): 1 mark for explaining that plastic consumption creates negative externalities, meaning MSB is less than MPB. 1 mark for explaining that the market overproduces/overconsumes at Qm compared to the socially optimal Qopt, resulting in welfare loss/market failure.

When a tariff is imposed on imported steel, the domestic price rises from the world price (\(P_w\)) to the tariff-inclusive price (\(P_w + t\)). This price increase causes domestic consumers to reduce their consumption from \(Q_4\) to \(Q_3\), leading to a contraction in consumer surplus (the area between the demand curve and the price line decreases). At the same time, the higher price encourages domestic steel producers to expand production from \(Q_1\) to \(Q_2\), increasing their revenues and resulting in an expansion of domestic producer surplus (the area between the domestic supply curve and the price line increases).

Diagram (2 marks): 1 mark for a correctly labeled tariff diagram showing domestic supply and demand curves, world price (Pw) and tariff price (Pw+t). 1 mark for showing the change in quantity demanded (Q4 to Q3) and quantity supplied (Q1 to Q2). Explanation (2 marks): 1 mark for explaining that the tariff increases price, causing consumer surplus to shrink as consumers pay more for a lower quantity. 1 mark for explaining that the higher price allows domestic firms to expand production, increasing domestic producer surplus.

An increase in domestic interest rates relative to other countries makes holding financial assets (like savings accounts or government bonds) in this country more attractive. Foreign investors seeking higher returns will move their funds into the country, a phenomenon known as 'hot money' inflows. To do this, they must buy the domestic currency, which increases the demand for the currency. In the foreign exchange market, this is represented by a rightward shift of the demand curve from \(D_1\) to \(D_2\). As a result of this increased demand, the equilibrium exchange rate rises, causing the currency to appreciate.

Diagram (2 marks): 1 mark for a correctly labeled exchange rate diagram with appropriate axes (Price of domestic currency in foreign currency, and Quantity of currency). 1 mark for showing a rightward shift of the demand curve (D1 to D2) leading to a higher exchange rate. Explanation (2 marks): 1 mark for explaining that higher interest rates attract foreign financial investment (hot money flows). 1 mark for explaining that this increases demand for the currency, causing it to appreciate.

An increase in consumer confidence means households are more optimistic about their future income and employment prospects. This optimism leads to a rise in consumer spending (\(C\)), which is a key component of Aggregate Demand (\(AD = C + I + G + (X-M)\)). Consequently, the AD curve shifts to the right from \(AD_1\) to \(AD_2\). In the short run, this increase in AD causes a movement along the upward-sloping Short-Run Aggregate Supply (SRAS) curve, resulting in an increase in the average price level (\(PL_1\) to \(PL_2\)) and an increase in real GDP (\(Y_1\) to \(Y_2\)) as firms produce more to meet the higher demand.

Diagram (2 marks): 1 mark for a correctly labeled AD/AS diagram with axes labeled Average Price Level (PL) and Real GDP (Y). 1 mark for showing a rightward shift of the AD curve along an upward-sloping SRAS curve, showing the new equilibrium. Explanation (2 marks): 1 mark for explaining that higher consumer confidence increases consumption (C), shifting AD to the right. 1 mark for explaining that this shift results in both a higher average price level and higher real GDP in the short run.

Definitions:
- Tariff: A tax imposed on imported goods and services.
- Infant Industry: A new industry in a country that is in its early stages of development and is not yet capable of competing internationally with established foreign producers.

Arguments for Tariffs (Benefits):
1. Learning by Doing and Economies of Scale: Infant industries need time to establish production efficiency, lower their average costs, and train their workforce. Temporary protection allows them to grow and achieve economies of scale.
2. Economic Diversification: Over-reliance on primary commodities exposes developing countries to price volatility. Protecting new manufacturing sectors helps diversify the economy and stabilize export revenues.
3. Employment Creation: Establishing new domestic industries creates jobs, boosts household incomes, and increases aggregate demand (AD).

Arguments against Tariffs (Drawbacks):
1. Incentive for Inefficiency: Protected firms may lose the incentive to innovate or lower costs because they are shielded from foreign competition. The 'temporary' protection often becomes permanent due to political lobbying.
2. Consumer Welfare Loss: Tariffs raise the price of imported goods from \(P_w\) to \(P_w + t\). Domestic consumers face higher prices and reduced choice, leading to a loss of consumer surplus.
3. Deadweight/Welfare Loss: Tariffs distort market signals, resulting in domestic production by less efficient producers (welfare loss) and a contraction in consumption (welfare loss).
4. Retaliation: Trading partners may impose retaliatory tariffs, harming the exporting sectors of the country implementing the protection.

Evaluation / Synthesis:
- Duration and Exit Strategy: The infant industry argument is theoretically valid but relies on the tariff being temporary. Governments must set a clear timeline for phasing out the tariff to force firms to become competitive.
- Alternative Policies: Subsidies may be more efficient than tariffs because they do not directly raise prices for consumers, though they place a burden on the government budget.
- Policy Selectivity: Governments must correctly identify which industries actually have a comparative advantage in the long run (avoiding 'picking losers').

Level Descriptors (15 Marks total):

- Level 1 (1–3 marks): The response indicates little understanding of the question. Terms are not defined, or definitions are incorrect. No relevant economic theory is presented.

- Level 2 (4–6 marks): The response shows some understanding. Relevant terms (tariff, infant industry) are defined. There is a basic attempt to explain the infant industry argument, but explanations are incomplete. A tariff diagram may be drawn but contains significant errors.

- Level 3 (7–9 marks): The response shows a clear understanding of the arguments. There is a sound explanation of how tariffs protect infant industries and the potential drawbacks (inefficiency, loss of consumer surplus). A correct tariff diagram is included and explained. The discussion is mostly descriptive and lacks a balanced evaluation.

- Level 4 (10–12 marks): The response is well-structured and balanced. It evaluates both the benefits (identifying the infant industry argument, diversification) and the costs (deadweight loss, inefficiency, retaliation). The diagram is fully integrated into the analysis. There is an attempt at synthesis, but the conclusion may lack depth.

- Level 5 (13–15 marks): The response meets all Level 4 criteria and demonstrates effective evaluation and synthesis. The conclusion provides a critical judgment on the conditions under which infant industry protection succeeds (e.g., exit strategies, choice of alternative policies like subsidies, political economy constraints).