households infer changes in prices from the utility bill. Importantly, while it has long been emphasized that this feature of residential energy markets plays an important role in shaping consumption responses to price changes (Shin [1985]), there is still little direct evidence on whether and how promptly energy consumption responds to price variations inferred from utility bills.

We complement and extend several strands of literature. A number of studies on the priceelasticity of energy demand employ time series methods using data on energy prices and aggregate energy consumption (Liu and Lin [1991]; Krichene [2002]; Bushnell and Mansur [2005]; Fezzi and Bunn [2010]). A related body of work draws on cross-sectional survey data, including influential papers by Parti and Parti [1980], Dubin and McFadden [1984], Dubin [1985] and Reiss and White [2005]. While these methods allow for the estimation of long-term impacts, the aggregated or cross-sectional nature of the data imposes relatively strong identifying assumptions. Furthermore, estimates yielded by cross-sectional data are, by construction, silent on the speed with which energy consumption adjusts to price shocks, an issue that is of key interest in a variety of policy contexts.

Another strand of research estimates price-elasticities in the context of tariff field experiments, including early work by Hausman et al. [1979], Acton and Mitchell [1980], Caves and Christensen [1980] and Parks and Weitzel [1984]. Whereas this approach addresses some limitations of the time-series and cross-sectional evidence, it has been criticized on the ground that the (most often voluntarily-selected) set of participants are thoroughly informed about price changes at the outset, generating an informational context that differs significantly from realworld situations in which households learn about price changes from utility bills or the press (Acton [1982]; Reiss and White [2008]).

Two recent papers using disaggregate billing data on electricity consumption from California are perhaps the closest to our own. Reiss and White [2008] examine how price shocks and conservation appeals impact residential electricity consumption. Their estimates point to sizable short-run impacts on energy utilization. In independent work, Ito [2013] exploits a spatial discontinuity in electric utility service areas in southern California, which leads to nearly identical households experiencing different nonlinear price schedules. His contribution is highly complementary to ours. Consistent with our results for the natural gas market, he finds that residential consumers in the electricity market respond to (lagged) average price, rather than marginal or expected marginal price.<sup>4</sup> The remainder of the paper is structured as follows. Section II provides background information on the market for natural gas in Greater Buenos Aires and describes the data employed. Section III describes the research design and provides important complementary evidence from a survey of consumers located near the tariff discontinuity of interest. Section IV presents the econometric results. Section V provides a discussion of the results in the context of the literature. Section VI offers some concluding remarks.

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