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Explore growth decomposition methods, sectoral contributions, and productivity trends. Includes case studies of Egypt, Mongolia, and Benin. Analyze returns on capital accumulation, factor shares, TFP, and sensitivity analysis.
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Growth Decomposition and Productivity Trends Leonardo Garrido and Elena Ianchovichina PRMED March 23, 2009
Possible growth decompositions • Contribution of demand components • Sectoral contribution to growth • Growth accounting
Contribution of Demand Components to Growth (I) • What are the proximate drivers of growth in aggregate demand? • Departs from fundamental equation Y=C+I+G+X-M • Aggregate supply = Y+M • Aggregate Demand = C+I+G+X • Steps: • Calculate annual growth rate of each component of aggregate demand • Calculate shares of each component of aggregate demand • Calculate the contribution to growth of each component by multiplying growth rates of demand components times share of component in aggregate demand
Contribution of Demand Components to Growth (II): The Case of Egypt.
Sectoral Contribution to Growth • Similar approach to demand contribution to growth • Uses GDP at factor costs (not at market prices) which equals the sum of GDP of economic activities • Imputed financial services not excluded from each economic activity (assumption of financial services proportion to sectoral GDP)
Growth Accounting (I) • With CRS Hicks Neutral Cobb Douglas production function • Taking logs and differentiating
Growth Accounting (II) • GDP data in real terms. All series to be expressed in same currency unit and base year • Factor shares: Obtained from National Accounts. a is the ratio of compensation to capital (Net operating Surplus) to total GDP at factor costs. • Assumption of CRS can be tested if times series of compensation to capital and labor are available for the analyzed period. • The labor share b (=1-a with CRS) can be calculated from National Accounts as the ratio of remuneration to labor to GDP at factor costs • Capital services are assumed to growth at same rate as capital stock (which implicitly says that no changes in capacity utilization occur during the analyzed period)
Growth Accounting (III) • Capital stocks (K) estimated from perpetual inventory method, given the depreciation rate (d) and the Investment flow (I): • Kt = Kt-1*(1-dt) +It • Capital Stock data available from Nehru and Dhareshwar (1993) • Employment data expressed in number of workers per year • If available, use number of hours worked by period • Human Capital accumulation proxy-ed by education attainment. With different categories of education (primary, secondary, tertiary) a Human Capital Index may be weighted by means of Returns to Education in each category. 8
TFP as a proxy to returns to capital accumulation • Problems with TFP (and growth accounting, in general) • TFP is a “measure of our ignorance” • Imperfect measures of factors of production • Natural resources not included • Factor shares as elasticities of output to changes in output constitutes a strong assumption • Is Cobb-Douglas an adequate functional form? • Alternative measures for returns on capital accumulation • Ratio of Net operating Surplus (From National Stocks) to capital stocks (estimated from perpetual inventory method)
Is the rate of return on economic activity low? • Assess TFP growth using growth decomposition at the aggregate level • Look at the TFP and factor accumulation trends • Look at the estimates in recent years and the final year • Conduct sensitivity analysis to see whether the finding are sensitive to changes in the qualitative findings • The aggregate TFP growth estimates may be misleading: it is important to look at sources of growth
The case of Mongolia.Efficiency has improved… Source: Ianchovichina and Gooptu (2007)
Sensitivity analysis • Productivity growth was positive in 2004 under: • Different values for the parameters • Different functional forms
Sectoral decomposition Not all sectors enjoyed high returns to capital • Returns to capital in manufacturing and transport were negative • Returns in agriculture were very volatile
What do these results tell us? • Growth in Mongolia has been narrowly-based • Driven by the booming mining and real estate sectors • Mongolia has remained vulnerable to terms-of-trade changes • Large part of Mongolia’s labor force employed in low-productivity activities
The case of BeninEfficiency has declined… Source: Ianchovichina (2008) based on the following assumptions: Cobb-Douglas production function with CRTS and capital share α=0.4.
Sensitivity analysis • Result for 2006 is robust to changes in specifications • We rule out the possibility that this productivity deterioration was due to negative TOT shocks as Benin’s TOT remained unchanged in the period 2003-06
Need to rule out exogenous shocks Source: Ianchovichina (2008) and Benin CEM, Chapter 1
Over the years Benin grew primarily through expansion of capacity, not more efficient use of existing capacity Source: Ianchovichina (2008) and Benin CEM, Chapter 1
Industry has stagnated…Key drivers of growth: agriculture and trade Source: Ianchovichina (2008) and Benin CEM, Chapter 1