In this unit we have given a broad outline of the techniques available that can be used to improve the usability of an interactive system. The question is: which technique is best? The answer is: it depends. The most important thing to realise is that there is no usability panacea. To be successful a developer must understand what techniques are good at and what they are not good at.

For example task analyses are good an analysing systems where the user has a set, explicit goal that they will try to achieve. They are not so good at analysing systems where the user acts in a more exploratory way. Task analysis would therefore not be very good at analysing web surfing systems, but would be much better at analysing an accountancy package.

The ultimate test of usability for a system is to analyse how users behave with it. What we will promote in this course is the idea that developers can design with users in mind, and therefore improve usability before getting to the evaluation stage. We are, however, not advocating designing interactive systems in isolation from users.

One of the main themes of this unit has been that making changes to system designs is fairly cheap and painless, whereas making changes to finished products is very expensive. Ideally we would recommend a design process where usability and usefulness are considered throughout the process. Therefore a system should be arrived at which is less likely to suffer from serious, large scale usability problems. Smaller scale interface issues can then be identified and dealt with by evaluation techniques.

There is no ‘right’ way of designing a system to be free of usability errors. The benefit of most of the techniques we have outlined in this unit are not that they tell a designer how to improve usability, but that they force the designer to think about the system from a ‘usability point of view’.

Below is a summary of the user centred design techniques we have discussed in the unit, stating in simple terms what they are good at and not good at. Once you have completed this course you should be more familiar with many of these techniques and should therefore be able to return to this table and add to and discuss it in more detail.