Jean Scholtz. (2004). Usability Evaluation

根據不同的evaluation資訊來源,可以區分三種usability evaluation model

  • evaluated by User
  • evaluated by Expert
  • evaluated by Models

執行usability evaluation 的步驟

  • design
  • conduct
  • analysis
  • report

三十年來,usability evaluation 學派的發展 前20年是使用者中心為主,90年代初期開始使用專家詮釋與認知分析模式建構。

User-Centered

  • identifying representative users, representative tasks, and developing a procedure for capturing the problems the users have in trying to apply a particular task.
  • two types evaluations are carried out in software development: in design phase(formative evaluations), and end of the development cycle(summative evaluations).
  • The Role of Usability Laboratories: to conduct evaluation.
  • Formative Evaluations: more informal in that the goal is to collect information to be used for design
  • Summative Evaluations: to document the usability characteristics of a software product.
  • Advantages and Disadvantages: representative problems; user evaluations are expensive and time consuming.

Expert-based

  • Methods: heuristic evaluation, guideline reviews, pluralistic walkthroughs, consistency inspections, standards inspections, cognitive walkthroughs, formal usability inspections, and feature inspections.
  • Guideline and Standards Reviews: A current set of guidelines for web sites is maintained by the National Cancer Institute (NCI). http://usability.gov/pdfs/guidelines_book.pdf
  • Cognitive Walkthroughs: to evaluate in the context of use in a real-world task.
  • Heuristic Evaluation: most widely used inspection method. Heuristic evaluation uses a small set of evaluators who judge a user interface for compliance with usability design principles.
  • Advantages and Disadvantage: less expensive and less time-consuming.

Visibility of system status Match between system and the real world User control and freedom Consistency and standards Error prevention Recognition rather than recall Flexibility and efficiency of use Aesthetic and minimalist design Help users recognize, diagnose, and recover from errors Help and documentation

Model-based

  • GOMS Models: Goals, Operators, Methods and Selection rules.
  • EPIC (Executive-Process/Interactive Control) system
  • ACT-R model: information foraging useful in evaluating information seeking in web sites is based on the ACT-R model
  • ACT-IF model was developed to use in testing simulated users interacting with designs for web sites and predicts optimal behavior in large collections of web documents
  • Advantages and Disadvantages: less expensive than empirical, user-centered evaluations, a necessary first step is conducting the task-level cognitive task analysis to use in producing model description. This is time consuming but can be used for testing many user interface designs.