2011年-IMF国际货币组织全球_Efficiency_36页_869kb

Summary of "Efficiency-Adjusted Public Capital and Growth"

Core Content

This working paper by Sanjeev Gupta, Alvar Kangur, Chris Papageorgiou, and Abdoul Wane explores the relationship between public capital and economic growth in 52 developing countries. It introduces a new measure of public capital stock that accounts for the efficiency of public investment, using the Public Investment Management Index (PIMI) to adjust for inefficiencies in project appraisal, selection, implementation, and evaluation. The paper contributes to the debate on public investment productivity by examining how different stages of the public investment process affect growth and capital accumulation.

Main Findings

• Public capital is a significant contributor to economic growth, though its impact varies across income groups.
• The income share of public capital is larger in middle-income countries than in low-income ones.
• However, the marginal product of public capital is relatively higher in low-income countries due to lower efficiency-adjusted capital stock.
• The quality of public investment, as measured by PIMI, is statistically significant in explaining variations in economic growth, particularly in low-income countries.
• Project selection and implementation are identified as key stages that influence the productivity of public capital and economic growth.
• The PIMI-adjusted public capital stock shows a downward trend compared to the unadjusted version, highlighting the inefficiencies in public investment.

Key Information

Public Investment Efficiency

• The PIMI is used as a proxy for the efficiency of public investment. It consists of 17 indicators grouped into four stages: appraisal, selection, implementation, and evaluation.
• The PIMI-adjusted public capital stock is constructed using the perpetual inventory method, with a time-invariant efficiency factor $ q_i $ that reflects the effectiveness of public investment processes.
• The formula used is:

$$
K_{it}' = K_{it-1}' - \delta_{it} * K_{it-1}' + q_i * I_{it-1}
$$

Where:

• $ K_{it}' $ is the efficiency-adjusted public capital stock.
• $ \delta_{it} $ is the depreciation rate.
• $ I_{it-1} $ is public investment spending.
• $ q_i $ is the PIMI score for country $ i $, ranging from 0 (no efficiency) to 1 (full efficiency).

Data Overview

• The study uses data from 71 countries over the period 1960–2009.
• Total investment and GDP data are sourced from the Penn World Tables (PWT) version 6.2.
• PIMI data are collected from Dabla-Norris et al. (2011) and cover the 2007–2010 period.
• The PIMI-adjusted public capital stock is lower than the unadjusted version, especially in low-income countries, due to inefficiencies in public investment.

Growth and Investment Trends

• GDP growth in low-income countries averaged 3.5% over the period 1960–2009, while middle-income countries had 4.3% growth.
• Public investment as a share of GDP was higher in middle-income countries (6.2%) than in low-income ones (4.4%).
• The growth rate of public capital stock was slightly lower in PIMI-adjusted series compared to the unadjusted one (2.8% vs. 4.1%).

Cross-Country Variations

• There is significant heterogeneity in public investment efficiency across countries.
• Low-income countries show a larger decline in effective public capital compared to middle-income countries, especially during the early decades.
• The PIMI-adjusted public capital stock in low-income countries fell by about 7 percentage points of GDP in the first decade, and later by over 40 percentage points.
• In contrast, middle-income countries saw a 10 percentage point increase in effective public capital during the 1970–1990 period.

Methodology and Analysis

• The paper employs panel regression analysis to examine the impact of public capital on growth.
• It uses static fixed effects and dynamic system GMM models to account for potential endogeneity and panel-specific effects.
• Robustness tests are conducted to validate the findings, showing that the results are consistent across different specifications.
• The effect of different stages of public investment is analyzed using alternative capital stock series, which exclude one of the four stages at a time.

Policy Implications

• Fiscal constraints such as financing and absorption capacity can limit the growth benefits of public capital.
• Public investment benefits in developing countries tend to be long-term, suggesting the need for extended debt sustainability frameworks.
• Institutional quality plays a critical role in the productivity of public capital, and improving the efficiency of the investment process can lead to greater growth outcomes.

Conclusion

The paper concludes that public capital is productive, but its impact is significantly influenced by the efficiency of the investment process. The PIMI-adjusted public capital stock provides a more accurate measure of the actual productive capital available, and the results suggest that improving institutional quality and efficiency in public investment can lead to more effective growth outcomes in developing countries.