Analyzing the effectiveness of Task Analysis with i*

1. Elizabeth Suescún Monsalve

2. Summary
 Introduction
 Limitations of the Notations
 Using a CDs to Evaluate i* Notational
System
 Using Empirical Evaluation to GOMS
 Extending i* to Support HCI Concepts
 Conclusions
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3. Introduction
 Task Analysis: is an approach that involves
different techniques addresses to describe
interaction between users and
environment in a systemic way.
 Framework i*: is a goal-oriented language
and RE notation.
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4. Introduction
 GOMS:
 Model is based on the mechanism of human reasoning
to solve problems;
 Represents activities (physical and mental) that involves
work.
Goals “user desires”
Operations basic units of perception, motor or
cognitive;
Methods Possibilities to reach operations.
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5. Introduction
 Hierarchical Task Analysis (HTA):
 Approach top-down which consider goals of
high-level and actions to reach goal.
 Goal is a desired state;
 Tasks describe how to reach this goal;
 Operations are lower-level units to describe
behavior;
 Plans which specify the conditions to perform
tasks or sub-tasks.
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6. Example decomposition of
task
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7. Typical example of GOMS
notations
GOAL: CLOSE-WINDOW
. [select GOAL: USE-MENU-METHOD
. MOVE-MOUSE-TO-FILE-MENU
. PULL-DOWN-FILE-MENU
. CLICK-OVER-CLOSE-OPTION
GOAL: USE-CTRL-W-METHOD
. PRESS-CONTROL-W-KEYS]
For a particular user:
Rule 1: Select USE-MENU-METHOD unless another
rule applies
Rule 2: If the application is GAME,
select CTRL-W-METHOD
If there is more than one alternative, we could suggest series of conditions and
rules to take the best options (Method):
METHODS: IF (EXPERT-USER)USE-KEYBOARD-METHOD
ELSE USE-MOUSE-METHOD
We could decompose the goals in subgoals:
GOAL: EDIT-DOCUMENT
GOAL: OPEN-DOCUMENT
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8. Limitations of the Notations
 Limitations on the Concepts:
 Design does not satisfy requirements (both)
 The option the user should chose (both)
 What tasks should be execute (both)
 What sequence should be followed in order to execute
some task (i*)
 How to finish some task execution (i*)
 Constraints are not represented (GOMS)
 Only considers error-free behavior (GOMS)
 The kind of user and his or her unpredictability are
disregard (GOMS)
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9. Limitations of the Notations
 Limitations on the Process
 the information related to system and user is
quite ad hoc. (Both)
 methodologies do not allow conflicts to be
identified between design decisions and
requirements. (Both)
 does not have some kind of traceability to
support the development of a design that
satisfies requirements (Both)
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10. Limitations of the i*
Graphical Notations
a) semiotic clarity;
b) symbols overload (homographs);
c) perceptual discriminability;
d) complexity management;
e) perceptual directness.
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11. Using a CDs Questionnaire to
Evaluate i*
Cognitive Dimensions Questionnaire:
 Goals:
 Evaluate the usability of information based-on
artifacts and notations;
 It is proposed as a user-centered discussion
tool in order to make quick but useful
evaluations.
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12. Considerations about
Evaluation of i*
CDs:
 Generated good concepts;
 Captured important aspects of i* framework
and its notational system;
 Allowed general users to make judgments and
reach agreement among themselves about i*
framework .
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13. Empirical Evaluation to
GOMS
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14. HTA Notations
Notation
Example
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15. Extending i* to Support HCI
Concepts
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16. Conclusions
 The main contribution of this work has
been to introduce framework i* as an
alternative to help process in HCI;
 The improvements propose in this are
intended to improve the communication
between different users;
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17. Conclusion
 In order to be more meaningful and
useful, task analysis should be developed
through and interdisciplinary collaborative
effort, involving the various viewpoint of
ER and HCI.
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18. Future works
 We propose to use Cognitive Dimensions Questionnaire to
evaluate GOMS;
 It is necessary to extend the empirical evaluation to identify
strengths and weaknesses of GOMS;
 It is required to make experiments using the modifications
proposes in i* notations;
 It necessary to make new analysis of i* notations but it
should be focused on visual representation aspects, which
the CDs framework had excluded.
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19. Thanks
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