The invention includes cohort analysis as an element of an in-vehicle navigation system. As an operator makes trips from an origin to a destination, the navigation system records various route segments chosen. These choices are compared to route segments comprising a minimal time route calculated for the trip. Segments not part of the prescribed route are collected and periodically sent along with the origin and destination to a centralized server, wherein they are stored in a database. The central server also has an extensive map database that lists many attributes for each segment not generally included in an in-vehicle database. The attributes include variables pertaining to traffic flow, e.g. speed, number of lanes, lane width; topology, e.g. possible turns at endpoints; geometry, e.g. horizontal shape, vertical curvature, and super-elevation; usage, e.g. freeway, arterial, local, residential, business; and topography, e.g. buildings, trees, open-space, facilities, and stores.