[LECTURE 8] Usability Engineering II

Usability metric

     Usability metric use to identify what it is going to measure for change scope of project. The usability metric use for understand user. It can use survey technique for prove "How good is the solution to find feasible or possible." It also can ask user like questionnaire or interview too.
Their are three criteria to define project :

Efficiency

     The efficiency is use for measure time, perform task and number of action required.


Effectiveness 

     The effectiveness use for measure the user problem. It can prove success or failure and also the quality of project.


Satisfying

     The satisfying use for measure user's satisfaction(Is it too difficult for user?). The satisfying base on learnability of user to measure user enjoy or not?


Learnability
     Learnability use for measure how easy it is to learn for use system. less time for learning system is good for learnability. If user use zero knowledge to use system is the best way.


Errors

     The intentional error is the perform action of user but the action was wrong (due to misunderstanding of the system). A slip is unintentional error like clicking wrong button. The errors can categorised in many kind of error such as;

• Minor errors : easy to find and fix it.
• Major errors : easy to find but harder to fix it.
• Fatal errors : error which prevent the task being complete.
• Catastrophic errors : error which other side effect like lost of data.

Time

     Time is one of measurement efficiency. It simply measure how long it take to perform task.