79 lines
3.1 KiB
Plaintext
79 lines
3.1 KiB
Plaintext
5. Direct Manipulation ("point and select")
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- visual representation of domain objects
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- direct action on objects
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- immediate and visible effects
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- reversible actions
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Discount usability engineering
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- a quick-and-dirty approach
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- basic premise: designs change substantially in early development phases
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- make a prototype that shows UI to get feedback early on
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- perfection is not cost effective
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- test early and often
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- how to do
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1. scenarios
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- task analysis
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- prototyping - partial
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- use paper & pencil or simple tools
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2. simplified thinking out loud
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- use 3-6 real users
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- ask user to think out loud while performing given tasks
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- collect data by note-taking
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User Analysis
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- learn by recognition, not recall
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- remember things in related groups
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- have different ways of learning and communicating
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- like to be in control
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pre-experience, such as KLM (Keyboard Level Model)
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provides numerical prediction of user performance
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primitive operations
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- physical actions
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- mental preparation
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K = 0.35 sec (hit key on keyboard, press button on mouse)
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P = 1.1 sec (point - move mouse to position)
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H = 0.4 sec (homing - move hand b/w kbd & mouse)
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M = 1.35 (mental preparation time)
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R = (responding - time for computer to respond)
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rules for using the M operator
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1. point and click (MPMK) => MPK (it is one cognitive unit)
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2. menu selection (MPK [File] MPK [Save]) => MPK PK (File on way 2 goal)
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3. typing (MK 'n' MK 'o' MK 't') => MKKK
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4. typing a terminator (MK 'a' K '.' K 'enter') => MKKK (bring closure)
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what KLM doesn't do
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1. errors
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2. learning time
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3. recall
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Usability:
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the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use
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Visibility:
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Making the user aware of the system’s components and processes, including all possible functionality and feedback from user actions.
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Reduce memory load
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Recognition/Recall
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the principle of visibility is based on the fact that we are better at recognition than we are at recall
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User testing
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Users were videotaped and timed when performing increasingly complex tasks
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Captured data including time taken, errors, help accessed, and task steps missed
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Heuristic evaluation
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Identify an interface error by predicting user problems it will cause
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Good at finding poor terminology and lack of clarity
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Ten heuristics are inadequate as a guide
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A subjective process
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End user testing
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Identify the symptom and infer its cause
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Good at finding problems while performing real tasks
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Task-based
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May miss features not encountered in tasks
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Users tend to blame themselves rather than the interface
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Both techniques share the same goals, but the actual results are quite different
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End user testing indicates the symptom of a problem
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Heuristic evaluation identifies its cause
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Heuristic evaluation helps analyze observed problems. But observation of novices is still vital as many problems are a consequence of the user’s knowledge, or lack of it.
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