Differential Diagnosis


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A presentation on heuristic testing

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Differential Diagnosis

  1. 1. Differential Diagnosis Minimal & In-depth Analysis UCD Team Hyderabad Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  2. 2. * what we’ll cover  Why diagnosis/evaluation is important  The three major types of diagnosis  How to perform a heuristic evaluation Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  3. 3. * why perform evaluations? Risk reduction  Evaluation and early redesign reduces the risk that final UI design will not meet users’ needs Cost and schedule savings  Much less expensive to fix user interface problems during early project stages  Can avoid schedule slippage due to user interface changes late in the project Best time for initial evaluation: BEFORE coding begins Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  4. 4. * major evaluation techniques Inspection: experts examine an interface  Example: heuristic evaluation Empirical: users involved  Example: usability testing (covered in evaluation class) Formal methods: analytical techniques  Example: Goals, Operators, Methods, Selection Rules Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  5. 5. * heuristics evaluation origins Developers of heuristic Used to quickly determine an application’s compliance evaluation: Jakob Nielsen with recognized usability principles known as “heuristics” Intended to be a cost-effective means of evaluating an interface (“discount usability”)  Increased speed of evaluation by using principles, not guidelines (higher level of abstraction)  Often can be performed when there is insufficient time for any other type of evaluation Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  6. 6. * heuristics evaluation: how to do it Identify 3 - 5 evaluators (inspectors) Tailor heuristics, and discuss tailoring so all evaluators understand heuristic usage Each evaluator independently:  Examines an interface and judges its compliance with heuristics  Rates the severity of each problem found After independent inspections, evaluators meet to:  Discuss findings  Eliminate duplicate problems  Agree on ratings and summary findings Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  7. 7. * severity ratings Combination of:  Frequency of occurrence  Impact if it occurs  One-time or persistent Also need to assess the market impact Nielsen recommends a 0 to 4 scale… 0: I don’t agree that this is a usability problem 1: Cosmetic only | 2: Minor | 3: Major | 4: Catastrophe Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  8. 8. * nielsen’s heuristics (1994)  Provide visibility into system status  Provide a match between system and real world  Allow both user control and freedom  Follow standards to ensure consistency  Prevent errors  Allow for recognition rather than recall  Provide flexibility and efficiency of use  Use an aesthetic and minimalist design  Help users recognize, diagnose and recover from errors  Provide help and documentation Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  9. 9. * description of heuristics  Visibility of System Status – The system should always keep user informed about what is going on, through appropriate feedback within reasonable time. searching database for matches  Match Between System and the Real World - The system should speak the user’s language, with words, phrases and concepts familiar to the user, rather than system- oriented terms. Follow real-world conventions, making information appear in a natural and logical order. Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  10. 10. * description of heuristics  User Control and Freedom - Users should be free to select and sequence tasks (when appropriate), rather than having the system do this for them. Users often choose system functions by mistake and will need a clearly marked “emergency exit” to leave the unwanted state without having to go through an extended dialogue. Users should make their own decisions (with clear information) regarding the costs of exiting current work. The system should support undo and redo.  Consistency and Standards - Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions. Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  11. 11. * description of heuristics  Error Prevention - Even better than good error messages is a careful design which prevents a problem from occurring in the first place.  Recognize Rather than Recall - Make objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  12. 12. * description of heuristics Edit  Flexibility and Efficiency of Use - Accelerators-unseen by the Cut novice user-may often speed up the interaction for the expert user such that the system can cater to both inexperienced and Copy experienced users. Allow users to tailor frequent actions. Provide Paste alternative means of access and operation for users who differ from the “average” user.  Aesthetic and Minimalist Design - Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility. Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  13. 13. * description of heuristics  Help Users Recognize, Diagnose, and Recover from Errors - Error messages should be expressed in plain language (NO CODES).  Help and Documentation - Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user’s task, list concrete steps to be carried out, and not be too large. Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  14. 14. * success is based on inspector skills Three types of inspectors identified by Nielsen  Domain expert  Usability specialist  “Double” expert Double experts find most problems  But you don’t have to be a UI expert to use this technique! Tends to find many problems of lesser severity  Thus severity ratings are important Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com
  15. 15. Thank You Nasarullah Khan Usability Engineer | User Experience Designer f:09959406614 e: khan_nasar@hotmail.com Nasarullah Khan f:09959406614 e: khan_nasar@hotmail.com