Question 1

What is the Harrod-Domar model and why was it important after World War II?

Accepted Answer

The Harrod-Domar model, proposed by Roy Harrod and Evsey Domar, provided newly independent nations with a simple framework for rapid economic development. It linked growth directly to saving rates and capital efficiency, offering policymakers a clear strategy for mobilizing domestic savings and directing them into productive investments during the post-colonial period.

Question 2

How does the saving rate affect economic growth in the Harrod-Domar model?

Accepted Answer

The saving rate represents the portion of national income set aside for investment. A higher saving rate means more resources are available for acquiring capital goods such as machinery, factories, or infrastructure. The model assumes all saved income is invested, increasing the capital stock and driving faster economic growth.

Question 3

What does the capital-output ratio measure and how does it influence growth?

Accepted Answer

The capital-output ratio measures how many units of capital are needed to generate one unit of output. It reflects capital productivity: a lower ratio means capital is being used more efficiently. The model shows that improving capital efficiency through better technology or infrastructure planning accelerates economic growth without requiring higher saving rates.

Question 4

What is the basic formula used in the Harrod-Domar model?

Accepted Answer

The Harrod-Domar formula is: Growth rate equals the saving rate divided by the capital-output ratio (g = s / v). For example, if a country saves 10% of income and has a capital-output ratio of two, its growth rate would be 5%. This simple equation shows that growth can be accelerated by increasing savings or improving capital efficiency.

Question 5

What key assumptions does the Harrod-Domar model make about investment and capital?

Accepted Answer

The model assumes all savings are automatically converted into investment, which increases the capital stock and leads to future output. It also presumes a fixed relationship between capital and output, meaning each unit of capital added contributes a constant amount of output. This deterministic relationship, while simplified, helped policymakers understand the importance of capital accumulation.

Question 6

Can you provide a numerical example of how the Harrod-Domar model calculates growth?

Accepted Answer

If a country saves 15% of its GDP and has a capital-output ratio of 3, expected growth is 5% (0.15 / 3 = 0.05). If the same country reduces its capital-output ratio to 2 through improved efficiency, growth rises to 7.5% (0.15 / 2 = 0.075). This demonstrates how either increasing savings or improving capital productivity accelerates development.

Question 7

How does the Harrod-Domar model relate to later growth theories?

Accepted Answer

The Harrod-Domar model established foundational principles about capital's role in growth that influenced subsequent theories. Later frameworks like the neoclassical growth model expanded on these ideas by incorporating additional factors such as technological advancement and examining long-run steady state conditions, building on the model's core insight linking investment to economic expansion.

ハロッド＝ドーマー・モデル I