Download presentation
Presentation is loading. Please wait.
Published byMalcolm Dorsey Modified over 8 years ago
1
Usability Engineering Dr. Dania Bilal IS 582 Spring 2007
2
NextPrevious Usability Engineering? Measures multiple components of the user interface Addresses the relationships between system and its users Focuses on the HCI field
3
NextPrevious What Is Usability Engineering? Bridges the gap between human and machines Measures the quality of a system in relation to its intended users Involves several methods, each applied at appropriate time of the design and development process
4
NextPrevious Importance of Usability The sooner problems are found, the less expensive it is to fix them –Saves money by reducing designers’ time Provides information about user experience –Cognitive, affective, and psychomotor Depends on method(s) employed
5
NextPrevious Importance of Usability Learn more about users, tasks, expectations, successes, failures, information seeking, etc. and take these into consideration in redesigning a system or designing new one
6
NextPrevious Usability Attributes As described by Neilsen –Learnability –Efficiency –Memorability –Errors & their severity –Subjective satisfaction
7
NextPreviousLearnability System must be easy to learn, especially for novice users –Hard to learn systems are usually designed for expert users –Learning curve for novice and expert users
8
NextPreviousEfficiency System should be efficient to use so that once the user has learned how to use it, the user can achieve a high level of productivity –Efficiency increases with learning
9
NextPreviousMemorability System should be easy to remember, especially by casual users –No need to learn how to use system all over again after a period of not using it
10
NextPreviousErrors System should have a low error rate System should provide user with a recovery mechanism –Minor errors –Major errors
11
NextPrevious Minor Errors Errors that did not greatly slow down user’s interaction with the system User is able to recover from them –through system feedback –through awareness of error made
12
NextPrevious Major Errors Difficult to recover from them Lead to faulty work if high in frequency May not be discovered by the user –Errors can be catastrophic
13
NextPrevious Subjective Satisfaction System should be likeable by users (affective) Satisfaction varies with purpose of system –Educational vs. entertainment
14
NextPreviousAssumptions The designer’s best guess is not good enough The user is always right The user is not always right Users are not designers Designers are not users More features are not always better Minor interface details matter Online help does not really help Source: Nielsen, J. (1993). Usability Engineering. San Diego: Morgan Kaufman.
15
NextPrevious Factors Influencing User Interaction Address the functionality of the system vis-à-vis: –user needs –user tasks –user information seeking –user expectations –user cognitive processes
16
NextPreviousEvaluation Component of usability engineering Involves users in the evaluation Users perform tasks developed by evaluator Main goal –Uncover problems and correct them
17
NextPreviousEvaluation Can be done before, during, and after system is designed and developed –Before design –During design –After release
18
NextPrevious Usability Methods: Cognitive Walkthrough Involves experts acting on behalf of actual users Goal- and task- driven of how user approaches a task in a system An observer “experimenter” is present –Prepares tasks –Takes notes –Provides help
19
NextPrevious Usability Testing Actual users interact with system Users perform tasks assigned by evaluator Users’ activities are captured –Methods Users may also be interviewed Captured data are coded, analyzed, and reported Interview data are coded, analyzed, and reported
20
NextPrevious Heuristic Evaluation Evaluators interact with an interface several times and map interface to specific heuristics or guidelines –See Neilsen’s ten heuristics Each evaluator generates a report Reports are aggregated and final report is generated An observer may be present
21
NextPrevious Field Studies Actual users Users are observed in naturalistic setting No tasks are assigned to users Users’ interaction with system are captured, analyzed, interpreted, etc. Interviews can be used in addition to observations
22
NextPrevious Usability Heuristics http://www.usabilityfirst.com/methods http://www.useit.com/papers/heuristic/heuristic_li st.html (Neilsen’s usability heuristics) http://www.useit.com/papers/heuristic/heuristic_li st.html http://www.useit.com/papers/heuristic/heuristic_e valuation.html (how to conduct a heuristic evaluation) http://www.useit.com/papers/heuristic/heuristic_e valuation.html http://www.uie.com/articles (collection of articles) http://www.uie.com/articles http://www.uie.com/articles/usability_tests_learn/ Learning about usability test (Jared Spool) http://www.uie.com/articles/usability_tests_learn/ http://www.useit.com/papers/heuristic/severityrati ng.html (Severity rating) http://www.useit.com/papers/heuristic/severityrati ng.html
23
NextPrevious Usability Tests Stages –Preparation –Introduction –User interaction and caputre –Debriefing Neilsen, J. (1993). Usability Engineering. San Diego: Morgan Kaufman.
24
NextPreviousPreparation Preparation for the experiment and data collection –Location of test (e.g., room to be used) –System to be used, capturing software, etc. –Test materials, instructions, questionnaires to be completed, as applicable
25
NextPreviousIntroduction Purpose of the test –Results will be used to improve interface User cnfidentiality & IRB Software and equipment used to collect data
26
NextPreviousIntroduction Users to ask questions before and during experiment –Type of questions accepted Users to report problems and difficulty in using system (e.g., screen freeze) May provide verbal instructions
27
NextPrevious Running the Test Experimenter(s) should refrain from interacting with users –Don’t give your personal opinion –Don’t tell user how to perform certain function –Don’t distract user during the interaction
28
NextPreviousDebriefing User is debriefed after the test Experimenter may follow up with questions about interaction –Likes, dislikes, comments, suggestions for system improvements, etc. Verbally (individual interview) –Structured or semi-structured Questionnaire with both closed and open- ended questions
29
NextPreviousDebriefing Experimenter ensures that data collected from each user are labeled –User is given a code or number for identification purposes Experimenter writes a brief preliminary report while events are still fresh Collected data are coded, analyzed, interpreted, and reported
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.