A PROPOSED INDEX OF USABILITY - A METHOD FOR COMPARING THE RELATIVE USABILITY OF DIFFERENT SOFTWARE SYSTEMS

Usability is becoming a more and more important software criterion. bu t the present usability measurement methods are either difficult to ap ply, or overly dependent upon evaluators' expertise. Based on human in formation processing theory, this study identified eight human factors considerations which are relevant to software usability. These consid erations as well as the three stages of human information processing t heory formed the framework from which our Purdue Usability Testing Que stionnaire (PUTQ) is derived. An experiment was conducted to test the validity of PUTQ. The experiment result showed high correlation betwee n PUTQ and the Questionnaire for User Interaction Satisfaction (QUIS v ersion 5.5). In addition, PUTQ detected the differences in user perfor mance between two experimental interface systems, but QUIS failed to d o so.