Prices as Proxies for Prices
经济理论所需的精确价格数据往往难以获得，许多应用研究使用区域或平均价格作为代理变量，但这会引入代理变量问题，即使代理变量与真实变量高度相关，规范错误等问题仍可能持续存在，不过可以通过添加额外变量来最小化规范错误的影响。
Abstract It is unusual for the precise price data required by economic theory to be available, and as a result, many applied studies use information on regional or average prices as proxies for the specific prices required. The use of one price as a proxy for another, however, introduces all the problems associated with the use of proxy variables into the analysis; and these problems may persist, particularly those associated with specification errors, even if the proxy is highly correlated with the true variable. It is possible, however, to minimize the impact of specification errors by adding additional variables.