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2b: Growth and structural change Overview Stylized facts of economic structure and structural change Simple 2-sector models of economic structure & change Classical development theory: the dual economy Neoclassical two sector model Growth and structural change Growth inevitably involves change in product mix of production, demand and trade Growth causes structural change: in the sectoral composition of GDP in the allocation of labor and other resources in the distribution of income by factors (L, K, etc) by households (rural, urban, etc) Growth & structural change: stylized facts In the poorest countries, agriculture generates largest share of income, employment and trade revenues The relative decline of agriculture is driven (in part) by economic expansion & growth of per capita income Demand changes: Engel effects Relative factor endowment growth rates (“Rybczinski effects”) Relative factor productivity differentials Policies & global markets may also play a role In general, poor countries tax agriculture to finance industrialization, reducing agr profitability and investment Global market prices may signal incentives for some sectors to expand, others to contract Policies that increase international integration may matter Tools: sectoral production functions Aggregate production function Y = F(K, L) Sector (industry) level production function Yj = Fj(Kj, Lj), for all industries j GDP (value-added):G = N PjYj= j=1 Factor employment: ∑ N j j jj P ∑j=1 F (K L) Total factor supply:L, K So full employment of factors constrains total output: Ex.: L€ =L1 + L2 + L3 Maximum output that can be produced subject to € constraints: production possibilities factor supply frontier € Growth implies outward shift of PPF Assume: M sector is K-intensive, A sector is L-intensive Growth: factor accumulation: ΔK, ΔL, orK, ΔK, ΔL, orL, or technical progress Faster rel rate of K accumulation Equal rates of K and L accumulation OR faster technical progress in manufacturing sector OR Equal rates of technical progress in both sectors A A M M 10 Agriculture ‘Balanced growth’ line - no str change D C Manufacturing Balanced growth: equal rates of K and L accumulation > equal growth rates of ag & mfg sectors 11 Agriculture ‘Balanced growth’ line - no str change D C Rise in GDP, measured in terms of manufactures at constant prices Manufacturing 12 Agriculture C E Manufacturing Unbalanced growth: faster rate of K accumulation faster relative growth rate of M sector • What happens to the composition of GNP? 13 Price changes and structural change • Exogenous change in world market price ratio Ex Food price rise: pA’ > pA, so pA’/pM > pA/pM Alters optimal mix of goods produced • Endogenous changes – Engel effects: As incomes rise, budget share of food diminishes – Domestic valuation of ag relative to mfg will decline; if prices are set in domestic markets, pA/pM will decline • Policies that alter prices Ex tariff at rate tM: pM(1+tM) > pM, so pA/pM(1+tM) < pA/pM 14 Agriculture E C Manufacturing 15 Is full employment constraint realistic in a poor economy? Structural change stories are driven in part by the need to ‘give up’ factors from one sector in order to permit another to expand Assume full employment of factors Much ‘hidden’ unemployment in low-income economies Ex.: in Vietnam, many rural and unskilled workers report working less hours than they would like “Classical” development models did not assume full employment 16 The dual economy model Examines growth and str change of an economy with surplus labor in agriculture Surplus labor: marginal product of labor in ag is initially zero Output sharing: each ag worker receives average product, not marginal product, so wage in ag > marginal product of L Can withdraw some labor without reducing total ag production Thus growth = expansion of industry, with unchanged ag output (compare Rybczinksi) What happens to sectoral GDP shares? 17 Industry wage Industry labor demands D1 Labor in industry L1M Wage in ag Subsistence ag wage = AP(L) Labor in ag Total ag.output (read from right to left) YA f L1A g h Labor in ag Industry wage Industry labor demands D1 L1 Wage in ag M D2 Labor in industry L2M Subsistence ag wage Labor in ag Total ag.output (read from right to left) YA f YA L1A L2A g h Labor in ag 19 Industry wage Industry labor demands D1 L1 Wage in ag M D3 D2 L2M L3 Labor in industry M Subsistence ag wage Labor in ag Total ag.output (read from right to left) YA f YA L1A L2A g YA L3A h Labor in ag 20 ... structure and structural change Simple 2-sector models of economic structure & change Classical development theory: the dual economy Neoclassical two sector model Growth and structural change... Vietnam, many rural and unskilled workers report working less hours than they would like “Classical” development models did not assume full employment 16 The dual economy model Examines growth and