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One of the reasons why interactive are not as easy to use as they might be is that there is not an process which ensures usability. In other fields there are processes that ensure a successful product, for example engineers do not guess whether the plane that they have designed will fly, they follow a process through, properties like lift generated by the wings, force generated by the engines, etc. so that they know whether their plane will fly. It is to do the same for usability. Firstly there is no general agreement on what usability is, so it is difficult to know if usability has been achieved, and it is to know what to measure or to measure it to ensure usability.

Without an agreed that ensures usability, engineers (who design and program interactive systems) end up whether the system is or ignoring the question altogether.