POM L5 Flashcards
(26 cards)
What are 5 activities of spiral model ?
- Determine objectives
- Evaluate alternatives
- Identify risks
- Resolve risks by assigning priorities to risks
- Develop a prototype for the highest identified risk
What are the main differences between waterfall model and spiral model ?
The Waterfall model assumes that once you are done
with an activity, all issues covered in that activity are
closed and cannot be reopened
# The Spiral model can deal with change between
activities, but does not allow change within an activity
Why Prototyping?
• Instant gratification • Helps understanding Improves poor communication • Allow early decision making • Mistakes are found early
What is Usability Testing ?
The act of disproving a model is testing , The act of testing a user interface is usability testing.
UT is watching a user interact with the user interface of the system
• Usability testing uses scenario-based design: Involves the creation of a test scenario, where the user performs a list of tasks while the observer watches and takes notes, and compares the observed with the specified behaviour
What is “Time-boxed” prototyping ?
it limits the duration of the
prototype development.
Horizontal Prototypes
- Show wide range of features
- Horizontal integration
- Bottom up, Top down
- Used inlinear processes:
- No full implementation up to the end
Vertical Prototypes
- Show small range of features (scenario, user story)
- Full implementation of these features
- Vertical Integration
- Used in agile processes
Revolutionary Prototyping (specification prototyping)
- Develop a prototype to get the requirements right
- then throw the prototype away and start from scratch
Advantage:
- Short production time
Disadvantage:
- Project might become very expensive (Users may fancy features in prototype that are expensive to implement)
Evolutionary Prototyping
- Prototype is the basis of final release
Advantage:
- Short time to the market
Disadvantage:
- Evolutionary prototyping can be used only if the target system can be constructed in the prototyping language
Illustrative Prototype
Develop the UI with story boards, and implement it on e.g. a napkin. (Good for first dialog with the client)
Functional Prototype
Implement and deliver a minimal functioning system.
Then add more functionality, ordered by risk. (Good for incremental development)
Exploratory Prototype (“Hack”)
Implement part of the system to get a clearer view on the requirements. (Good fro paradigm breaks)
Evaluating prototypes
- Heuristic Evaluation can start in development phase
- HE works on sketches, papers etc.
- “Missing-element” problems are harder to find on sketches
- HE is a usability engineering method to find usability
problems in a user interface design
The difference between HE and Usability Testing is like the difference between walkthrough and inspection
What are the Risks of Prototyping?
- User may become attached to Prototype
- Customer might not appreciate the hard work to turn prototype into final deliverable
- User might confuse prototype with final product
- prototype development might be costly
- Negative feelings can occur if prototype doesn’t work
What is Usability ?
Measures how well a user can use the system functionality. Categories:
- Learnability (a system is better if it is easier/faster to learn)
- Number of steps
Usability Management
- Learnability
- Efficiency
- Memorability
- Error handling and Robustness
- Satisfaction(User experience)
Cycle Time
The time to accept an input and produce an output
Models in User Interface Design
- System Model: how the system really works
- (User) Interface model: Model of the system presented to the user
- User Model: How the user thinks the system works
- Design Model: Model in the designer’s head realized in the Interface model
Managing human error, what are the two main categories in this field?
- Mistake: Trying to do something the system cannot do (novice users, with the wrong user model) - Slip: made by expert user when distracted. Three main types: - Description error - Capture error - Mode error
Slip Example: Description Error
Happens when two actions are similar. The intended one is replaced by the similar one with many functions in common.
Design Model recommendation: Avoid actions
with very similar descriptions.
Slip Example: Capture Error
A sequence of actions is replaced by another sequence that starts the same way.
Design Model recommendation: Avoid habitual action sequences with common prefixes.
Slip Example: Mode Error
Mode Error: States in which actions have different meanings (insert mode vs command mode)
Design Model Recommendation: Try to eliminate modes
What are Nielsen’s 10 Heuristics?
How can we categorise them?
We categorise the 10 Heuristics in 4 main categorise.
Meet expectations:
1. Match the Real World (speak the user language, use metaphors)
2. Maintain Consistency
3. Provide good Help and Documentation
The User is the boss:
- User Control and Freedom
- Visibility of System Status
- Flexibility and Efficiency
Handle errors:
- Error Prevention
- Recognition, Not Recall
- Error Reporting, Diagnosis and Recovery
Keep it simple:
10. Aesthetic and Minimalist Design.
Heuristic Evaluation
Basicsteps
• Evaluator inspects the User Interface thoroughly
• Compares User Interface against the Nielsen’s 10 heuristics
• Provides a list of usability problems.
