Design Issues

As the design of a user interface evolves 4 general design issues almost always surface system response time user help facilities command labeling and bugs’ information handling. Sadly, several designers do not address these issues until relatively late in the design process sometimes the first linking of a problem does not occur until an operational prototype is available. Unnecessary interaction project customer and delays frustration 2 almost always result. It is far better to build was as a design issue to be considered at the starting of software design when changes are costs and easy are low.

System response time is the main complaint for several interactive systems. In common system response time is measured from the point at that the user performs some control action example for hits the return key or clicks a mouse until the software responds with desired output or action.

System response time has 2 main characteristic that are: variability and length. If the length of time for system response time is too long user frustration and stress is the inevitable result. Moreover a very brief response time can also be detrimental if the user is being paced through the interface. The rapid response may force the user to rush and thus make mistakes.

The Variability refers to the deviation from average response time and in various ways it is the more important or the response time characteristics. The Low variability enables the user to build a rhythm even if response time is relatively long. Example for 1 second response to a command is preferable to a response which varies from 0.1 to 2.5 seconds. The user is always wondering always off balance whether something dissimilar has occurred beyond the scenes.

All user of a computer-based system interactive  needs help now and then in some cases a simple question addressed to a knowledgeable colleague can do the trick. In others information research in a multivolume group of user manuals may be the only option. In several cases moreover modern software gives on line help facilities which enable a user to accumulate a question answered or resolve a problem without leaving the interface.

Two distinct type of facilities are encountered integrated and add on. The integrated help facility is designed into the software from the starting. It is often circumstance sensitive enabling the user to select from those topics which are relevant to the actions presently being performed. Obviously, this decrease the time needed for the user to obtain help and raise the friendliness of the interface. An add-on help facility is added to the software after the system has been established. In several ways, it is really an on-line user's manual with limited query capability. The user may have search by a list of 100 of topics to find appropriate guidance often making many false revenging and starts much irrelevant information. There e is little doubt which the integrated help facility is preferable to an add-on approach.

The number of design issues must be addressed when a help facility is considered:

• Options include a separate window a reference to a printed document and a 1 or 2 line suggestion produced in a fixed screen location. How will help be represented?

• Options contain help only for a subset of all actions and functions and help for all functions. Will help be available for all system functions and at all times of during system interaction?

• Options include data help menu a special function key and a HELP command. How will the user request help?

• Options include are turn button displayed on the screen and a control sequence or function key. How will the user return to normal interaction?

• Options include a flat structure in that all information is accessed by a keyword a layered hierarchy of information which provides increasing detail as the user proceeds into the structure and the use of hypertext. How will help information be structured?

Warning and Error messages are bad news delivered to users of interactive systems when something has gone away. On their warning impact and worst error messages useless or misleading information and serve only to increase user frustration. Little computer users have not encountered an error of the form;