Lecture 3: State Transition Networks (STNs)

Question 1

What is a State Transition Network (STN)?

Answer 1

A state transition network (STN) is a method of dialogue analysis on the interface. One STN should be used for each use case scenario.

Question 2

What are the three things a State Transition Network (STN) will capture?

Answer 2

1. State - a moment in time
2. Transitions - trigger that causes change in state
3. Paths - prescribed sequence(s) through state

Question 3

What are the 5 State Transition Diagram?

Answer 3

1. Abstract Diagram
2. Visual Interface Diagram
3. Annotated Diagram
4. Indexed Diagram
5. Branching Diagram

Question 4

What is an ABSTRACT State Transition Diagram?

Answer 4

An abstract diagram captures the flow of user activities as abstractions, there are no visual details and they are easy to modify.

Question 5

What is a VISUAL INTERFACE State Transition Diagram?

Answer 5

A visual interface diagram captures appearances as it passes through each state, good for details but is harder to modify.

Question 6

What is an ANNOTATED State Transition Diagram?

Answer 6

An annotated diagram is a state transition diagram which is augmented to include explanatory text.

Question 7

What is an INDEXED State Transition Diagram?

Answer 7

An index diagram is a diagram which is used to manage complexity an multiple possibilities.

Question 8

What is a BRANCHING State Transition Diagram?

Answer 8

Most interfaces contain decision paths which leads to multiple transitions. Branching diagrams can be used along with abstract, visual interface and indexed diagrams to identify the (multiple) decisions paths and transitions.

Question 9

What are the three issues regarding State Transitions Networks?

Answer 9

1. A diagram can become too complex.
2. Limited when modelling current concurrent dialogue
3. No simple method for modelling special actions, e.g. Esc. and Help function.

Question 10

What are the two uses of a State Transition Network?

Answer 10

1. State Transition Networks provide a documentation of interaction scenarios that implement use cases of the system.
2. States and actions can be analysed to ensure designs are sound and effective.

Question 11

What is contextual task analysis?

Answer 11

Contextual task analysis is a study of users current tasks and workflow patterns. Results in a description of current tasks, workflows, understanding and specification of underlying user goals.

Question 12

What are the 3 actions properties in regards to the use of dialogue analysis and state transition networks (STNs)?

Answer 12

1. Completeness
2. Non-determinism
3. Consistency

Question 13

What are the 2 state properties in regards to the use of dialogue analysis and state transition networks (STNs)?

Answer 13

1. Reachability

2. Reversibility