The big data era facilitates the use of new online data sources in both academic and professional fields: In real estate, for instance, private Web data such as online property price estimates have become commonly used sources for investigating property markets. The quality of such data, however, has not been routinely assessed. This article therefore statistically analyzes the quality of Web data for mapping local property prices. To do so, it compares property estimates drawn from ten Web sites and property prices calculated from the Demande de Valeurs Foncières central state tax services database for a stratified sample of sixty French municipalities. This study reaches a paradoxical conclusion and theorizes it as a shift from market opacity to methodological opacity: Although it has become easier to obtain property price estimates at a local level, this commodified form of information is hardly suitable for geographical research on local property markets due to its varying, unpredictable quality. The partially disclosed or even missing metadata and methodologies make it indeed impossible to identify the sources of biases (sampling or stock vs. flow effects). The article shows that this methodological opacity is directly linked to the strategic role of copyrighted information in a context of property market reintermediation.

中文翻译：

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从市场不透明转向方法不透明：网络数据是否足以用于法国房地产市场监控？

大数据时代促进了新的在线数据源在学术和专业领域的使用：例如，在房地产领域，在线房地产价格估算等私人网络数据已成为调查房地产市场的常用来源。然而，此类数据的质量尚未得到常规评估。因此，本文统计分析了用于绘制本地房地产价格的 Web 数据的质量。为此，它比较了从 10 个网站得出的财产估计值和从 Demande de Valeurs Foncières 中央国家税务服务数据库计算的 60 个法国城市的分层样本的财产价格。这项研究得出了一个矛盾的结论，并将其理论化为从市场不透明到方法不透明的转变：尽管在当地获得房地产价格估计变得更加容易，但这种商品化的信息形式很难适用于当地房地产市场的地理研究，因为其质量多变且不可预测。部分公开甚至缺失的元数据和方法确实无法确定偏差的来源（抽样或存量与流量效应）。文章表明，这种方法论的不透明性与版权信息在房地产市场再中介化背景下的战略作用直接相关。部分公开甚至缺失的元数据和方法确实无法确定偏差的来源（抽样或存量与流量效应）。文章表明，这种方法论的不透明性与版权信息在房地产市场再中介化背景下的战略作用直接相关。部分公开甚至缺失的元数据和方法确实无法确定偏差的来源（抽样或存量与流量效应）。文章表明，这种方法论的不透明性与版权信息在房地产市场再中介化背景下的战略作用直接相关。