Usability Evaluation in Educational Technology


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Usability Evaluation in Educational Technology

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Usability Evaluation in Educational Technology

  1. 1. Usability Evaluation in Educational Technology Prepared for class presentation by: Dr. Alaa Sadik ILT, SQU [email_address] Dillon, A. (2001) Usability evaluation. In W. Karwowski (ed.) Encyclopedia of Human Factors and Ergonomics, London: Taylor and Francis .
  2. 2. The Concept of Usability <ul><li>The concept of usability has been defined in multiple ways, usually on one of the following bases: </li></ul><ul><li>Semantics: usability is equated to terms such as ease of use or user-friendliness , without formal definition of the properties of the construct. </li></ul><ul><li>Features: usability is equated to the presence or absence of certain features in the user interface such as Windows, Icons, Menus or Pointing devices. </li></ul><ul><li>Operations: usability is equated to terms such as performance and affective levels manifest by users for certain task and environmental scenarios. </li></ul>
  3. 3. What is Usability? <ul><li>Usability is a measure of interface quality that refers to the effectiveness (?) , efficiency (?) and satisfaction (?) with which users can perform tasks with a tool (see Handout 1 for more info). </li></ul>
  4. 4. Methods of Evaluation Usability <ul><li>There exist three methods of evaluating usability depending on available resources and the stage of development of the system under review. </li></ul><ul><li>User-based </li></ul><ul><li>Expert-based </li></ul><ul><li>Model-based </li></ul>
  5. 5. Methods of Evaluation Usability <ul><li>User-based </li></ul><ul><li>A sample of the intended users try to use the application. </li></ul><ul><li>Subjects are asked to perform a set of tasks with the technology. </li></ul><ul><li>Performing a set of pre-determined tasks is generally considered to yield the most reliable and valid estimate of an application's usability. </li></ul>
  6. 6. Methods of Evaluation Usability <ul><li>Expert-based </li></ul><ul><li>Refers to any form of usability evaluation which involves an expert examining the application for a given user population. </li></ul><ul><li>Users are not employed and the basis for the evaluation lies in the interpretation and judgment of the evaluator. </li></ul>
  7. 7. Methods of Evaluation Usability <ul><li>Types of expert-based </li></ul><ul><li>Heuristic evaluation </li></ul><ul><ul><li>Provides a list of guidelines which the evaluator uses to examine the system and while following a typical path through a given task. The evaluator reports violations of the guidelines as likely user problems. </li></ul></ul><ul><li>Cognitive walkthrough </li></ul><ul><ul><li>The evaluator first determines the exact sequence of correct task performance, and then estimates the likely success or failure of the user in performing such a sequence. </li></ul></ul>
  8. 8. Methods of Evaluation Usability <ul><li>Model-based </li></ul><ul><li>Apply an analytical model to user sequence to calculate the index of usability. </li></ul><ul><li>A cognitive psychology-derived framework that casts user behavior into a sequence of fundamental units (such as moving a cursor to given screen location or typing a well-practiced key sequence) which are allocated time estimates for completion based on experimental findings of human performance from psychology. </li></ul>
  9. 9. Comparisons of Methods - Measures only one component of usability - Limited task applicability - Provides rigorous estimate of usability criterion - Can be performed on interface specification Model-based - Expert-variability unduly affects outcome - May overestimate true number of problems <ul><li>- Cheap </li></ul><ul><li>Fast </li></ul>Expert-based - Time consuming - Costly for large sample - Requires prototype to occur - Most realistic estimate of usability - Can give clear record of important problems User-based Disadvantages Advantages Usability method
  10. 10. Conclusion <ul><li>Usability evaluation is a core component of user-centered systems design and an essential competency for professionals working in the software domain. Choosing among methods is largely a matter of determining what information is needed and at what stage in the development cycle is the evaluation to occur. </li></ul>