for example: Gassner et al., 2008<sup>1</sup> ; Nagayama, 2010<sup>2</sup> ; Erdogdu, 2014<sup>3</sup> ; Jamasb et al., 2014<sup>4</sup> ; Urpelainen and Yang, 2017.<sup>5</sup> Moreover, an evaluation of the impact of reform would not have been feasible to implement in any meaningful depth given the scope of the data set covering 88 countries over a 25‐year period. Rather, the primary contribution of this paper is to provide a much more detailed characterization of the content, timing and sequencing of power sector reform measures than has previously been possible.

The remainder of the paper is organized as follows. Chapter 2 presents the methodology, while Chapters 3 through 6 report the findings on the regulation, restructuring, competition and private sector participation measures of reform, respectively. In Chapter 7 the four dimensions of reform are drawn together to distill the overall findings of the analysis, before concluding in Chapter 8.

# **2. Methodology**

This paper draws on a number of data sources to create an unprecedented time series data set comprising information on which countries adopted which types of power sector reforms at which dates. The database covers 88 developing countries for the period 1995 to 2015. Complementary information for 22 OECD countries is available for a subset of variables and time periods. An important source of data is the RISE (Regulatory Indicators for Sustainable Energy) project,<sup>6</sup> which provides an up to date snapshot of power sector reform globally based on numerous indicators on the power sector structure and institutional arrangements in 2015. A second important source of data is the World Bank’s Private Participation in Infrastructure database,<sup>7</sup> which records all developing country transactions involving the private sector going back into the 1990s, and makes it possible to understand how private sector participation has evolved over the same period. Important historic reference points are provided by comparable earlier surveys conducted by Besant‐Jones (2006) and ESMAP (1999).

The paper will first individually examine the diffusion of each of the four dimensions of power sector reform: regulation, restructuring, competition and private sector participation. Along each of these four dimensions, a number of stages of reform are identified, which make it possible to examine diffusion trends over time as well as the geographic patterns of uptake. The prevalence of power sector reform in developing countries is compared to that in developed countries over the same time frame.

The final section of the paper turns to drawing out the main conclusions and insights from looking across experiences on all four dimensions of reform. The ways in which different types of reforms are packaged

> 1 Gassner, K., A. Popov, and N. Pushak. 2008a. “Does the private sector deliver on its promises? Evidence from a global study in water and electricity”. _Gridlines 44512_ . PPIAF, The World Bank, Washington D.C.

> 2 Nagayama, H. 2010. “Impacts on investments, and transmission/distribution loss through power sector reforms”. _Energy Policy_ , 38(7), 3453‐3467.

> 3 Erdogdu, E. 2014. “Investment, security of supply and sustainability in the aftermath of three decades of power sector reform”. _Renewable and Sustainable Energy Reviews_ , 31, 1‐8.

> 4 Jamasb, T., R. Nepal, G Timilsina, and M. Toman. 2014. Energy Sector Reform, Economic Efficiency and Poverty Reduction, Discussion Papers Series 529, School of Economics, University of Queensland, Australia.

> 5 Urpelainen, J., & Yang, J. 2017. Policy Reform and the Problem of Private Investment: Evidence from the Power Sector. _Journal of Policy Analysis and Management_ , 36(1), 38‐64.

> _6 http://rise.esmap.org/_

> _7 https://ppi.worldbank.org/_

5