User Centred Design (UCD) is an approach that supports the entire development process with user-centred activities, in order to create applications which are easy to use and are of added value to the intended users.
Industry surveys have clearly shown that the majority of failed projects can be attributed to incomplete or inaccurate requirements. The biggest cost benefit that UCD can provide is by more accurately defining requirements.
A design changes made late in the design process will typically cost ten times more than if identified during requirements. Making changes to working systems will cost about one hundred times more.
Ideally UCD activities should be integrated with other development activities. They should be planned and managed by the development team. Over time, UCD activities will become common practice, and existing members of the team will be able to carry them out. However, usability skills will most probably be needed within the project and if necessary one or more members of the team should possess these skills.
There are four important UCD principles:
These principles have an impact on four project phases within the development process:
UCD need not be extensive or expensive. A few simple activities early in development will significantly reduce the overall cost of developing an acceptable system.
UCD activities should be tailored to meet the needs of an project or organisation and take into account the relative importance of usability in each individual situation.
Usability is only valuable if it supports business objectives. It is important to start by identifying and prioritising which user issues will contribute to the success of the project.
It is also important to identify business resources and constraints (time, money, skills and facilities) to make sure the user centred design plan fits in.
The next step is to identify in detail who will use the system, and how it will be used. If this information is not easily available, field research may be needed to obtain more detail.
Usability requirements can take the form of how accurately user complete their tasks, how long they take and how satisfied they are. A new system should at least be as good as any existing or competitive system or there is a significant risk of project failure.
The difference between UCD and other approaches is that UCD methods are used to develop simple models, mock-ups or prototypes on parts or all of the designs (graphical designs, information architecture, interaction design, information visualisation)
Prototypes are used as touch-points with users to keep checking that design concepts and solutions are on course from a user perspective. The risk of developing a solution that doesn’t work is thus minimised.
Usability effort should focus on providing feedback on the acceptability to users of design solutions while they are being developed.
The most valuable form of feedback is through evaluating design solutions with typical users.
As design solutions are assessed, feedback of results should be fed back to the designers quickly. The objective is to improve the design based on user feedback. Iterative design implies a process of design, evaluation, redesign.
Evaluation activities should begin early in development and continue in frequently througout.