Flashcards in POM L5 Deck (26):
What are 5 activities of spiral model ?
1. Determine objectives
2. Evaluate alternatives
3. Identify risks
4. Resolve risks by assigning priorities to risks
5. 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
• 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
• Show wide range of features
• Horizontal integration
• Bottom up, Top down
• Used inlinear processes:
• No full implementation up to the end
• 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
- Short production time
- Project might become very expensive (Users may fancy features in prototype that are expensive to implement)
- Prototype is the basis of final release
- Short time to the market
- Evolutionary prototyping can be used only if the target system can be constructed in the prototyping language
Develop the UI with story boards, and implement it on e.g. a napkin. (Good for first dialog with the client)
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)
- 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
- Error handling and Robustness
- Satisfaction(User experience)
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?
Trying to do something the system
cannot do (novice users, with the wrong user model)
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.
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:
4. User Control and Freedom
5. Visibility of System Status
6. Flexibility and Efficiency
7. Error Prevention
8. Recognition, Not Recall
9. Error Reporting, Diagnosis and Recovery
Keep it simple:
10. Aesthetic and Minimalist Design.
• Evaluator inspects the User Interface thoroughly
• Compares User Interface against the Nielsen's 10 heuristics
• Provides a list of usability problems.
What model you need to use regarding changes in the project ?
Frequent changes: Agile Process
Infrequent changes: Spiral model
No changes: Waterfall model