Objective and Subjective Methods for Evaluating the Usability of Schematic Maps: The Case Against Informal Expert Assessments

Schematization is an established method to improve transit map usability, especially for rail-based modes. However, official designs differ considerably in the application of such methods, leading to the question of whether some designs might be better optimized than others. Objective measurements of performance comparing the use of different versions currently offers the soundest method of determining usability, especially compared with soliciting subjective evaluations from the general public – which are typically uncorrelated with objective measures. A short-cut to design evaluation might be to consult experts in the domains of cartography or graphic design. However, the research discussed here indicates that informal expert-evaluations are almost indistinguishable from those offered by the general public. In order to be given credence, expert-evaluations of usability must be derived from generalized empirical evidence, or else grounded in clearly stated, falsifiable theories of usability, or at least based upon logically transparent arguments.