Chapter 6 TASK ANALYSIS

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CEB 3013 Human Computer Interaction
TASK ANALYSIS
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What is Task Analysis?
The process of analyzing the way people perform
their jobs.
Things they need to do
Things they need to know
Things they need to act on
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What is Task Analysis?
Things we do
IN ORDER TO CLEAN THE ROOM
Get the vacuum cleaner out(from storeroom, for
instance) Fix the appropriate attachment/parts. Cl
ean the rooms. When the dust bag gets full, empty
it. Put the vacuum cleaner and tools away
Things we need to know
Things we act
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DEFINITIONS
Goal
A state of a system that the human wishes to
achieve.
Task
A structured set of activities in which actions
are undertaken in some sequence.
Action
A task that involves no problem solving or
control structure component.
Plan that consists of a number of tasks or
actions linked into a sequence. It can be tools
or techniques to achieve goal. Consists of
iteration and selection.
Method
Object
The focus of actions. ex focus to bold text is
text.
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A general model for task analysis
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TASK ANALYSIS APPROACHES

• Task decomposition.
• task is split into subtasks.
• Knowledge-based techniques.
• based on the knowledge of certain object, the
  actions and how that knowledge is organized.
• Entity-relation-based analysis.
• emphasis on identifying the actors or objects and
  the relationship between them.

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Hierarchical Task Analysis (HTA)
TASK DECOMPOSITION (HTA)

• Use to view the graphical representation of a
  decomposition of a high level task into subtasks
  and operations or action.
• Involves an iterative process of identifying
  tasks, categorizing them, break into subtasks.
• Aim
• to describe the task in terms of a hierarchy of
  operations and plans.
• Help to specify the conditions under each subtask
  needs to be carried out.

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Structure chart notation
example of checking if a word is wrong when
undertaking a spell check
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THREE STAGES IN TASK ANALYSIS

• 1. Starting the analysis
• (a) Firstly, the area of work or main task
  should be specified.
• (b) The main task should then be broken down into
  between four and eight between subtasks.
• These subtasks should be specified in terms of
  objectives and between them should cover the
  whole area of interest.
• (c) Next, the subtasks should be drawn out as
  layered plans, ensuring that they are logically
  and technically correct and that none is missing.

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THREE STAGES IN TASK ANALYSIS

• 2). Progressing the analysis
• (a) Decide the level of detail that is required
  and what point to stop the decomposition.
• Range from a a very fine level of description,
  in which individual keystrokes (e.g 'click
  mouse') are outlined, to a higher level, in which
  basic units of activity described (e.g. 'delete a
  block of text').
• (b) Make a decision as to whether to continue by
  analyzing each subtask in turn to the required
  depth (depth-first analysis) or to work on the
  next level along and analyze each subtask in turn
  (breadth-first analysis).
• (c) Use numbering convention and the pragmatic
  form.

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THREE STAGES IN TASK ANALYSIS
3. Finalizing the analysis (a) Ensure that the
decompositions and the numbering of the tasks are
consistent. (b) Present the analysis to someone
else who has not been involved in the
decomposition analysis but who knows the tasks
well to check for consistency
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Example of Human Task Analysis (HTA)

• O. make a cup of tea
• 1. Boil water
• 1.1 Fill kettle
• 1.2 Put kettle on stove
• 1.3 Wait for kettle to boil
• 1.4 Turn off gas
• 2. Empty pot
• 3. Make pot
• 4. Wait 4 or 5 minutes
• 5. Pour tea
• Plan 0. Do 1
• at the same time, if the pot is full 2
• then 3-4
• after four or five minutes 5
• Plan 1. Do 1.1-1.2-1.3
• when kettle boils 1.4
• Plan 2.
• .
• Plan 5.

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0 make a cup of tea
Plan 0 do 1 at the same time, if the pot is full
2 then 3-4 after four or five minutes 5
5 pour tea
4 pour boiling water
3 put tea in pot
2 empty pot
1 boil water
Plan 1 1.1-1.2-1.3 when kettle boils 1.4
1.4 turn off gas
1.3 wait for kettle to boil
1.2 put kettle on stove
1.1 fill kettle
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Sources of information and data collection
1. Documentation - e.g. existing manuals,
instruction booklets, the training materials,
rule books and job descriptions etc for the task.
2. Observation - either formal or informal, is
essential to get an understanding of the task
situation. At the simplest level the analyst can
simply spend time watching people and chatting,
just to get the 'feel of the task. 3. Interview -
questioning domain experts is often a direct and
quick way to get information about a task. The
expert could be the person who knows about the
job and also, the person who actually does it. 4.
Initial analysis - the detailed analysis depends
on the analysis method employed, but most start
by trying to build up lists of elementary objects
and actions. 5. Sorting and classification -
several of the techniques include the production
of hierarchies and sorting of entries by various
attributes.
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Uses of task analysis

• 1. Manuals and tuition
• The hierarchical structure of HTA can be used to
  structure manuals or course material.
• This kind of how-to-do-it manual is often
  useful for initial training, but for structuring
  a course, or for more advanced training material,
  a more conceptual structure is better.
• Task analysis can also be used to help a user
  transfer from one system to another.

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Uses of task analysis

• 2. Requirements capture and system design
• Task analysis can be used to guide the design of
  new systems.
• Task analysis of an existing system can help in
  two ways.
• First, the analyst can ask which of the
  existing objects, tasks, etc should be in the new
  system?.
• Secondly, the formalized presentation of the
  existing state of affairs may help the client to
  clarify what the novel features are to be. It may
  be decided to automate whole tasks or roles, or
  simply specific subtasks.

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Uses of task analysis

• 3. Detailed interface design
• Task sequences obtained from a task
  decomposition can be used when designing the
  systems dialog.
• The order in which subtasks are performed in the
  system can be made to mirror that of the original
  job. Even where the interface style is more user
  directed, hence the dialog sequence is not
  defined by the designer, the task decomposition
  and plans are useful.
• If we know that a certain task is frequently
  performed, then we want it to be easy for the
  user to perform the subtasks in the appropriate
  order.
• Task analysis is never complete and hence it
  should not be the sole arbiter of the style and
  structure of an interface. However, the insights
  from a well-executed task analysis can make an
  interface that easily supports the way people
  want to work.

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An example Task Analysis for aMicrowave oven
What is the overall goal? Cook food! How
is this done? Prepare meal Put meal in oven
Select programme Listen for bell to ring
Remove meal
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An example Task Analysis for aMicrowave oven

• Selecting a programme - How is this done?
• Set to autosensor
• Set to defrost
• Set timer to cook
• What are the rules that influence the order in
• which tasks/subtasks take place? (the plans)..

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HTA for using a Microwave
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Task Analysis and Design Example

• Design a cash operated machine for quick and easy
  purchase of tickets by rapid transit passengers.

• Activity model
• State destination
• Journey type (one way/ return)
• Get fare quote
• Get ticket and change

• Initial Solution
• Purchase ticket
• Determine fare
• State destination
• State journey type
• Receive fair
• Obtain ticket
• Pay money
• Receive ticket
• Receive change

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Task Analysis and Design Example

• Refinement
• There are two machines
• Fare quoting machine
• Ticket dispensing machine

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Task Analysis and Design Example
0 Purchase ticket
Plan 0. Do 1- 2
1 Determine fare
2 Obtain ticket
Plan 1. Do 1.1- 1.2 -1.3
Plan 2. Do 2.1- 2.2
2.2 Receive ticket and change
2.1 Pay money
1.3 Receive fare quote
1.1 State destination
1.2 State destination
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Task Analysis and Design Example
Indicate Journey Type One way Round-trip
Choose Destination Kelana jaya Sri
petaling Seputih Kuala Lumpur Seremban Kajang Shah
Alam Port Kelang Seri Setia PWTC
RM
Deposit money
coins
notes
Lift for ticket and change