Case Study Improving the user-friendliness of a directory of chemical substances: the Approved Supply List

The purpose of this study was to improve the usability of the Approved Supply List, an alphabetical directory of chemical substances containing a series of entries each having a number of standard elements. The original directory consisted of two printed volumes in different formats and involved a two-stage look-up procedure using both volumes. Three new single-volume alternatives were devised, each of which allowed any substance to be looked up alphabetically by name in one operation. These were compared with the original using a timed look-up task and in-depth interviews with a panel of 24 regular users of the directory. Results showed that all three new versions were used almost twice as fast as the original, and were preferred. An A4 layout with two sequences of entries per page was selected for further development, and alternative treatments of typographic detail were assessed by a further 12 users. The improved usability of the final result was accompanied by a reduction of around 45 per cent in the number of pages in the directory, representing considerable savings in paper and distribution costs. The development and testing of alternative prototypes with a panel of users led to a design solution that could not have been arrived at simply by analysis of problems with the original version.