中文摘要
一个追求利润最大化的垄断者为试图了解某一参数的用户策划构建一个数据库。用户有两种类型：“即时预测者”希望了解该参数的当前值，而“预测者”则瞄准其长期值。数据存储涉及一个不变的边际成本。垄断者设计一个由费用和数据访问水平所描述的合约菜单。利润最大化的菜单提供对历史数据的完全访问，同时向即时预测者完全提供当前数据，但可能对预测者保留当前数据。与社会最优相比，垄断者保留过多历史数据、保留过少当前数据，并且总体上可能存储过多数据。（JEL C53, C80, D42, L12, L86）
Abstract
A profit-maximizing monopolist curates a database for users seeking to learn a parameter. There are two user types: “Nowcasters” wish to learn the parameter's current value, while “forecasters” target its long-run value. Data storage involves a constant marginal cost. The monopolist designs a menu of contracts described by fees and data-access levels. The profit-maximizing menu offers full access to historical data, while current data are fully provided to nowcasters but may be withheld from forecasters. Compared to the social optimum, the monopolist keeps too much historical data, keeps too little current data, and may store too much data overall. (JEL C53, C80, D42, L12, L86)