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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


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

- Short production time
- 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

- Short time to the market
- 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:
4. User Control and Freedom
5. Visibility of System Status
6. Flexibility and Efficiency

Handle errors:
7. Error Prevention
8. Recognition, Not Recall
9. Error Reporting, Diagnosis and Recovery

Keep it simple:
10. Aesthetic and Minimalist Design.


Heuristic Evaluation

• 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


What is affordance ?

refers to the properties that
determine how the thing could be