We see much discussion of late about how the importance of not only preserving scientific data but making data freely accessible. It is surely the case that much valuable data, produced at great cost, is subsequently discarded. But making data accessible incurs a cost (in some cases, a substantial cost). Thus, any systematic program aimed at preserving more data requires some systematic process for deciding what data is worth keeping.
I suggest that we can usefully approach the question of data preservation from an economic perspective. Data costs money to collect or create, a cost that may depend on both the data d involved and the time t at which it is created: thus,