Criteria for Selecting Methods in User Centred Design

The ISO TR 16982 technical report which provides guidance on the use of usability methods is being revised as ISO 9241-230. This paper describes the procedure currently being suggested for selecting user-centred design methods. The best practices in ISO PAS 18152 are prioritised based on the assessed benefits and risks, then the most appropriate methods to achieve the best practices are identified. SELECTING USER-CENTRED DESIGN METHODS Previous approaches to methods selection have focussed on the strengths and weaknesses of individual methods (e.g. [3]), and their cost benefits (e.g [1]). However the reason for using usability methods is to make specific contributions to usercentred design. As Wixon [6] says, “the goal is to produce, in the quickest time, a successful product that meets specifications with the fewest resources, while minimizing risk”. “In the world of usability work on real products embedded in a corporate and business framework, we must focus on factors of success, such as how effectively the method introduces usability improvements into the product.” The approach suggested in this paper is to first identify the necessary user centred design activities, then select the most appropriate methods based on the design and organisational context. The proposed steps needed to select user-centred methods for a project are: 1. Identify which categories of human-system (HS) best practice activities in Annex A can increase business benefits or reduce project risks. For any category of system development activity in column 1 of Annex A, the UCD professional can reference the best practice activities in column 2 (and read the explanation of them in ISO PAS 18152 if necessary). They can then use Annex C to help judge to what extent carrying out or not carrying out these activities will influence the final usability of the product, and hence result in potential business benefits from improved usability, or in project risks from inadequate usability [2]. 2. For the selected categories of best practice activities choose the most appropriate methods: a) To what extent will each possible method listed in column 3 of Annex A achieve the best practices? NOTE This relies on the expertise of the UCD professional supported by the documentation of the methods, such as that being developed by the Usability Body of Knowledge [5]. b) How cost effective is each possible method likely to be? The most cost-effective methods can be selected by using Annex B to identify the method types, and then taking account of the associated strengths, weakness and constraints of each method type (examples of which are given in Annex D): • Constraints: time, cost, skills available, access to stakeholders and other users (Tables 4, 5 and 8 from 16982). • The nature of the task: complexity, amount of training required, consequences of errors, time pressure (Table 6 from 16982). • The nature of the product: whether new, complexity (Table 7 from 16982). • Context of use: range of contexts, how well understood (Table 9, to be done). The selection of appropriate methods can be carried out as part of project planning, and may also be reviewed prior to each system development activity. As the development of ISO 9241-230 is in the early stages, feedback on this proposed approach s welcomed.