A decade long experience shows that the monitoring of the performance of public and private monopolies in South America is proving to be the hard part of the reform. The operators control most of the specific information needed for regulatory purposes and have little interest in volunteering their dissemination unless they have an incentive to do so. This paper argues that, in spite of, and maybe because of, a much weaker information base and governance structure, Latin America's electricity

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... tor could rely on an approach that relies on performance rankings based on comparative efficiency measures. The paper shows that with the rather modest data currently available publicly, such an approach could already yield useful results. It provides estimates of efficiency levels in South America's main distribution companies between 1994 and 2000. Moreover, it illustrates how relatively simple tests can be used by regulators to check the robustness of their results and strengthen their position at regulatory hearings.