Economic growth Study Guide

📖 Core Concepts Economic Growth – Increase in both the quantity and quality of goods/services a society produces; measured by real (inflation‑adjusted) GDP or GDP per‑capita. Growth Rate – Geometric annual change in real GDP (or per‑capita GDP) between two points in time. Intensive vs. Extensive Growth – Intensive: higher output from better use of existing inputs (labor, capital, technology). Extensive: higher output from more inputs (larger population, more land). Labor Productivity – Output per unit of labor input; the single biggest driver of per‑capita growth. Human Capital – Skills, knowledge, health, and abilities of workers; often proxied by schooling years, test scores, literacy. Physical Capital – Buildings, machinery, equipment used in production; subject to diminishing returns. Innovation & Creative Destruction – New products/technologies generate demand and replace old ones, sustaining long‑run growth. Institutions – Property rights, rule of law, and political systems that shape incentives for investment and innovation. --- 📌 Must Remember Real GDP per‑capita = Total real GDP ÷ Population. Solow‑Swan Production Function: $$Y = K^{\alpha}(AL)^{1-\alpha},\qquad 0<\alpha<1$$ Romer’s Knowledge‑Augmented Function: $$Y = A K^{\alpha} L^{1-\alpha},\quad A\text{ = accumulated ideas}$$ Rule of 72: Doubling time (years) ≈ 72 ÷ annual growth % . Solow’s Key Predictions: diminishing returns to capital, convergence to a steady‑state unless technology (A) improves. Endogenous Growth Insight: Returns can be increasing because ideas/knowledge are non‑rival and have spillovers. Malthusian Trap – Pre‑industrial growth: tech ↑ → population ↑, but per‑capita income stays flat. Piketty’s r > g – When the return on capital (r) exceeds growth rate (g), wealth inequality rises. Health‑Growth Loop: Better health → longer working lives → more human‑capital investment → higher productivity → higher income → more health spending. --- 🔄 Key Processes Calculating Real Growth Rate Obtain nominal GDP for two years. Deflate using a price index (CPI or GDP deflator). Compute \(\frac{\text{Real GDP}{t} - \text{Real GDP}{t-1}}{\text{Real GDP}{t-1}}\times100\). Solow‑Swan Convergence Determine capital‑to‑worker ratio \(k = K/L\). Apply \( \dot{k}= s f(k) - (n+\delta)k\) (s = savings rate, n = population growth, δ = depreciation). Steady‑state when \(\dot{k}=0\) ⇒ \(s f(k^) = (n+\delta)k^\). Human‑Capital Accumulation Investment in schooling: \( \Delta H = \text{schooling years} \times \text{quality factor}\). Returns realized over longer working life (adjust for mortality). Innovation Cycle (Schumpeterian) R&D → New product/technology → Temporary monopoly profit → Creative destruction of old tech → Spillovers → Higher total factor productivity (TFP). Policy Decision for Growth Strategy Low‑income, capital‑scarce country → prioritize big‑push infrastructure & education. Middle‑income with stagnant growth → shift to endogenous policies: R&D subsidies, IP protection, skill upgrading. --- 🔍 Key Comparisons Intensive vs. Extensive Growth Intensive: ↑ productivity, usually sustainable; relies on tech/skills. Extensive: ↑ inputs (pop., land); limited by resource availability. Solow (Exogenous) vs. Endogenous Growth Solow: technology \(A\) grows outside the model; long‑run growth only via \(A\). Endogenous: \(A\) is a function of R&D, human capital, policy → growth can be policy‑driven. Malthusian vs. Post‑Malthusian (Unified Theory) Malthusian: tech ↑ → pop. ↑, income per‑capita flat. Post‑Malthusian: fertility decline + human‑capital rise → tech ↑ raises per‑capita income. Inequality Effects (Classical vs. Modern) Classical: inequality ↑ → saving ↑ → capital ↑ → growth ↑. Modern (Galor‑Zeira): inequality ↓ → credit access ↑ → human‑capital ↑ → growth ↑ (especially after industrialization). --- ⚠️ Common Misunderstandings “More capital always means faster growth.” Diminishing returns set in; without tech progress, extra capital yields little output. “GDP growth = better living standards.” After a threshold, extra growth may have little welfare gain (Threshold Hypothesis). “Higher GDP automatically reduces inequality.” Growth can be pro‑rich; distribution depends on institutions and policies. “Innovation only creates jobs.” Creative destruction can displace workers in old sectors while creating new ones elsewhere. --- 🧠 Mental Models / Intuition “Production Engine” – Think of an economy as a machine: capital = the engine, labor = fuel, technology = the spark plug. Adding fuel helps until the engine hits its limit; only a better spark plug (tech) can push the whole system farther. “Investment Ladder” – Early stages: climb by building roads, schools (big‑push). Mid‑stages: climb by R&D and patents (endogenous). Top stages: climb by improving institutions and governance (innovation‑friendly). --- 🚩 Exceptions & Edge Cases Resource‑rich small economies may experience Dutch disease: resource boom raises income but crowds out manufacturing, lowering long‑run growth. Countries with high mortality colonization → extractive institutions → persistent low growth despite natural endowments. Very high inequality can actually boost growth in early industrialization (physical‑capital‑driven) but harm it later (human‑capital‑driven). --- 📍 When to Use Which Growth Accounting → Use Solow’s decomposition when you have data on capital, labor, and TFP to identify sources of growth. Policy Design → Deploy big‑push (infrastructure, mass schooling) when the economy is stuck in a low‑productivity trap; shift to endogenous (R&D subsidies, IP protection) once basic capital thresholds are met. Inequality Diagnosis → Apply classical view for agrarian/early‑industrial settings; apply modern (Galor‑Zeira) framework for mature, knowledge‑based economies. --- 👀 Patterns to Recognize “Productivity‑Population Offset” – In long‑run data, spikes in productivity are often followed by population growth that dampens per‑capita gains (Malthusian pattern). “Sectoral Shift Curve” – As an economy grows: agriculture ↓ → manufacturing ↑ → services ↑, with manufacturing’s employment share eventually falling as automation rises. “Innovation‑Demand Feedback” – New products → higher consumer demand → higher output → more resources for further R&D (positive loop). --- 🗂️ Exam Traps Confusing growth rate with level – A high growth rate on a tiny economy does not mean a large absolute increase. Mistaking “GDP per‑capita” for “standard of living” – Ignoring distribution, health, and environmental costs can mislead. Attributing convergence to “catch‑up” alone – Forget the role of technology diffusion; without it, convergence stalls. Assuming “more capital = higher growth” in Solow – The model’s steady‑state shows that without tech improvement, capital deepening stops increasing output per worker. Mix‑up between “intensive” and “extensive” – Intensive improvements are quality‑driven; extensive are quantity‑driven. ---