Instead of an actual physical space, in IR, we are predominately concerned with accessing information within a collection of documents (i.e., information space), and instead of a transportation system, we have an Information Access System (i.e., a means by which we can access the information in the collection, like a query mechanism, a browsing mechanism, etc). The accessibility of a document is indicative of the likelihood or opportunity of it being retrieved by the user in this information space given such a mechanism.
After reading a pre-print of my HCIR 2009 position paper about the information availability problem, Vinay pointed me at follow-up work he’d done with Leif on information retrievability. I agree with his observation that, while I look at information availability from a user-centric perspective; they consider retrievability from a document- or system-centric perspective. The approaches are complementary, and both add to a growing body of work that advocates a holistic model of how users access information, rather than a narrow focus on reductionist measures like precision and recall at the level of individual queries.
To be clear, those reductionist measures still have their place. In fact, I’m looking forward to NIST‘s Ellen Voorhees defending Cranfield next month to an HCIR crowd that is, for the most part, deeply suspicious of it.