Expert-based methods (Heuristic method)

Procedure:

• Experts are assigned as evaluators who test the application or the program.
• A list of criteria is defined (heuristics), which are to be met and which must not be breached. Examples of criteria are "system status is shown" – the user should always know what the system is doing - or "meaningful error messages" – instead of producing incomprehensible number codes when something goes wrong it should produce clearly understandable error messages.
  
• An example of a heuristic list can be found according to Nielsen (1994) and Schluep (2004) at: Heuristic list (doc, 26 kB, in German).
• Independent of one another and using the heuristic list, the experts identify the program's weaknesses , they document difficulties associated with using the software and describe how one or several more are not met.
• The assessments are compiled and weighted according to importance (for example as "very urgent" or "marginal").
• Finally, a summary of results is reported to the client.

Conclusion
The expert-based method is simple, quick and low-cost. However, an evaluation by experts should not replace a test performed by "genuine" users (say, in a pilot study). In the development phase, it can be still used as a diagnostic tool for difficult problems.

Further instruments and information

• An instrument originally designed to compare different websites: Web Usability Index (Harms, Schweibenz & Strobel, 2002).
• The "Society for Technical Communication" provides various instruments for usability checklist on the following website: http://www.stcsig.org/usability/resources/toolkit/toolkit.html (click there on the link: e-learning-checklist.doc)