Capital Accumulation & Economic Growth
Physical capital—machinery, infrastructure, and equipment—is central to the Solow growth model. Investment increases the capital stock, raising productivity until diminishing returns kick in. Higher saving and investment rates should lead to faster growth during the transition to steady state and higher long-run output per worker.
The Solow model predicts a positive relationship between investment rates and growth, especially for countries far from their steady state. We test this prediction using cross-country panel data.
📈 The Solow Prediction
Higher investment rates are associated with higher growth, but the relationship weakens over time (transitional dynamics). Countries far below their steady-state benefit most from increased capital accumulation.
⚠️ Diminishing Returns
Neoclassical theory predicts diminishing returns to capital. As capital-labor ratios rise, each additional unit of capital contributes less to output—explaining why capital deepening alone cannot sustain long-run growth.