Heuristic Evaluation. Heuristic evaluation evaluates the interface to identify usability problems against recognized usability design heuristics.

Transcription

1 Heuristic Evaluation Heuristic evaluation evaluates the interface to identify usability problems against recognized usability design heuristics. Usability heuristics are best practices developed and identified from common design problems across many systems.

2 Procedure A set of evaluators (3-5 is about optimal) evaluate a UI (some training may be needed) Each one independently checks for compliance with the heuristics Different evaluators find different problems Evaluators then get together and merge their findings Collectively rate severity of the problems Debriefing/brainstorming how to fix the problems (and point out what s really good)

3 Preparing the evaluators If system is intended to be walk up and use or the evaluators are domain experts, no particular training is needed Otherwise, evaluators may need some knowledge about the domain and scenarios

4 Evaluation Each evaluator goes through the UI at least twice First, get an overall feel for the system Second, inspect the various interface elements and consider them in terms of the heuristics May use a supplementary-list of domain-specific guidelines

5 Debriefing Review findings with project team and evaluators Prioritize issues Discuss general properties of UI, incl. good points Brainstorm potential improvements to fix major usability problems Development team rates how much effort each fix would require

6 Severity ratings Used to allocate resources to fix problems Based on Frequency the problem will occur Impact of problem (hard or easy to overcome) Persistence (will users learn a work around) 1 cosmetic problem 2 minor usability problem 3 major usability problem; important to fix 4 usability catastrophe must fix

7 Heuristic Evaluation Deliverables List of issues: What heuristic(s) was/(were) violated What is the severity What is the cost to solve the issue

8 Pros / Cons + Cheap (no special lab or equipment) + Easy + Fast (about 1 day) + Cost-effective + Detects many problems without users + Complementary to task-centered approaches + Coverage + Catches cross-task interactions - Requires subjective interpretation - Does not specify how to fix problems - Performance improves as evaluator knowledge increases

9 Nielsen s heuristics 1. Visibility of system status Current state information and feedback of actions should be clear. 2. Match between system and the real world Electronic processes should logically flow similar to real world processes. 3. User control and freedom Users should have the freedom to recover from an incorrect action. 4. Consistency and standards Follow conventions to ensure users are not confused if the labels or actions mean the same thing.

10 Nielsen s heuristics 5. Error prevention Remove error-prone aspects to minimize errors rather than feedback when an error occurs. 6. Recognition rather than recall Provide visible cues, don t rely on the user recalling a bit of obscure information. 7. Flexibility and efficiency of use Provide shorthand options for expert users, and help for novice users. 8. Aesthetic and minimalist design Feedback should not contain irrelevant, extra information.

11 Nielsen s heuristics 9. Help users recognize, diagnose, and recover from errors Error messages should provide information of the cause and potential solutions of the problem. (i.e. NOT Error a.5 ) 10. Help and documentation Help screens and documentation should be context aware and searchable.

12 Gerhardt-Powals heuristics 1. Automate unwanted workload Eliminate calculations, estimations, comparisons and any unnecessary thinking. 2. Reduce uncertainty Data should be clearly presented to avoid confusion. 3. Fuse data Summarize low and high level data together where appropriate. 4. Present new information with meaningful aids to interpretation New information should be presented within familiar frameworks.

13 Gerhardt-Powals heuristics 5. Use names that are conceptually related to function Display and labels should be context aware. 6. Group data in consistently meaningful ways Logically group related data together on a screen, and be consistent with other screens. 7. Limit data-driven tasks Limit time needed assimilating raw data. (i.e. use color, graphics) 8. Include in the displays only that information needed by the user at a given time. Only display the information needed for the current task.

14 Gerhardt-Powals heuristics 9. Provide multiple coding of data when appropriate Provide data in various formats/levels for different users. 10. Practice judicious redundancy When principles 6 and 8 conflict, it may be necessary to include extra information.

15 Weinschenk / Barker classification 1. User control User perceives that they are in control and have the controls they need. 2. Human limitations The user interface should not overload a user s cognitive, visual, auditory, tactile or motor limits. 3. Model Integrity The interface will fit tasks within whatever modality is being used. 4. Accommodation The interface will fit the way each user group works and thinks.

16 Weinschenk / Barker classification 5. Linguistic clarity The interface should communicate as efficiently as possible. 6. Aesthetic integrity The interface should have an attractive and appropriate design. 7. Simplicity The interface should be as simple as possible. 8. Predictability The interface should function in a way that the user can correctly predict what will happen.

17 Weinschenk / Barker classification 9. Interpretation The interface should make reasonable guesses about what the user is trying to do. 10. Accuracy The interface should be free of errors. 11. Technical clarity The interface should be clear as possible. 12. Flexibility The interface should allow the user to adjust the design for custom use.

18 Weinschenk / Barker classification 13. Fulfillment The interface should fulfill the user s needs. 14. Cultural Propriety The interface should match the user s social customs. 15. Suitable Tempo The interface should operate at a tempo suitable to the user. 16. Consistency The interface should be internally consistent.

19 Weinschenk / Barker classification 17. User support The interface should provide help as needed or requested. 18. Precision The interface will allow the users to perform the tasks as needed. 19. Forgiveness The interface should provide the user to recover from an error. 20. Responsiveness The interface should give feedback on results and status.