HCI Designing Systems for People 
In order to design an effective interface, it is necessary to know the answers 
to the following: 
  Who is the user? 
  What is the task? 
  What is the environment in which the system will operate? 
User classification
There are 3 main types of user 
  Novice 
  Knowledgeable / intermittent user 
  Expert / frequent user 
Users can however, be classified in any other way that is appropriate to the system being built. Some users may have keyboard skills, others not. Some users may have knowledge of other similar systems, others not. The advantages of classification mean that generalisations can be made about users and their needs. This doesn’t necessarily mean that the best system has been designed for every individual. It means that the system has been designed to fit the generalisations for each user group.

The Novice
For the novice user of a system, progress is slow because of the limitations of working memory. Chunking is almost entirely absent. Systems used by novices require more feedback and more opportunities for closure. 

Knowledgeable / intermittent users
These users need consistent structures, good help facilities, good 
documentation. 

Expert users 
These users have fast response time and will require brief feedback. Experts organise their knowledge according to a higher conceptual structure. They can recall more than novices because their knowledge is chunked. (see table) Expertusers will look for keyboard shortcuts, abbreviated sequences. Experts can find constant confirmation screens irritating. Use these only when important. 
>Logging on according to the experts view and the actual steps 

      Expert steps for logging on Actual steps for logging on 
      Input username Press any key to activate screen 
      Input password Press return key 
      ... Input menu choice 
      ... Press return 
      ... Input username 
      ... Press return 
      ... Input password 
      ... Press return 
      ... Wait for welcome message 

 
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