evaluation techniques 技术衡量.ppt

chapter 9 evaluation techniques Evaluation Techniques Evaluation tests usability and functionality of system occurs in laboratory, field and/or in collaboration with users evaluates both design and implementation should be considered at all stages in the design life cycle Goals of Evaluation assess extent of system functionality assess effect of interface on user identify specific problems Evaluating Designs Cognitive Walkthrough Heuristic Evaluation Review-based evaluation Cognitive Walkthrough Proposed by Polson et al. evaluates design on how well it supports user in learning task usually performed by expert in cognitive psychology expert ‘walks though’ design to identify potential problems using psychological principles forms used to guide analysis Cognitive Walkthrough (ctd) For each task walkthrough considers what impact will interaction have on user? what cognitive processes are required? what learning problems may occur? Analysis focuses on goals and knowledge: does the design lead the user to generate the correct goals? Heuristic Evaluation Proposed by Nielsen and Molich. usability criteria (heuristics) are identified design examined by experts to see if these are violated Example heuristics system behaviour is predictable system behaviour is consistent feedback is provided Heuristic evaluation `debugs design. Review-based evaluation Results from the literature used to support or refute parts of design. Care needed to ensure results are transferable to new design. Model-based evaluation Cognitive models used to filter design options e.g. GOMS prediction of user performance. Design rationale can also provide useful evaluation information Evaluating through user Participation Laboratory studies Advantages: specialist equipment available uninterrupted environment Disadvantages: lack of context difficult to observe several users cooperating Appropriate if system location is dangerous or impractical for constrained single user systems to allow control