Costs of production and dissemination

The cost effectiveness of having information in hypertext form should be considered. Conventional IR systems allow only retrieval while hypertext systems help users integrate units of information retrieved.

Evaluation should also include looking for the availability of automated tools or cognitive prostheses to overcome cognitive overhead and disorientation. Readers adapt different navigation strategies based on the complexity of the task at hand. Such tools might help with a variety of subtasks related to hypertext usage. These subtasks might include specifying search targets and planning the order in which information will be sought. Tools are also required to store and manipulate the information found in order to integrate with other work. However, the effectiveness of such tools might be reduced due to the following :

• Readers may not realize they need help.
• Readers may not know how to use such tools.
• Readers might blindly follow certain procedures without understanding their need.

Hence, the design and evaluation of hypertext systems should include the understanding of how people use their cognitive resources to handle information.

Nielsen also has discussed four categories for the evaluation of hypertext documents [Nielsen, 1991]. These are:

Utility

This is a measure of whether the hypertext document actually helps a user perform the intended task. This has to be compared with performing the same tasks with linear text. Many empirical tests have shown that readers exhibit poorer performance with hypertext than with paper documents.

Integrity

This is a measure of the completeness of the document - whether it is up to date and not misleading and if it is easy to maintain.

Usability

Usability can be measured as a combination of these factors:

Ease of learning

It is a measure of how fast a reader can start learning and navigating through a hypertext document. Good presentation structure and graphic design are key determinants.

Ease of use

It is a measure of how fast a reader can locate information. Appropriately defined links, search mechanisms, backtracks, landmarks and other navigational aids can greatly increase efficiency of use.

Error handling

It is a measure of how many errors a reader makes and how easy it is for them to recover from such errors.

Aesthetics

This is a measure of how pleasing is the system to the user.