Human-Computer Interaction 3e Dix, Finlay, Abowd, Beale

exercises  -  15. task models

EXERCISE 15.11 [extra - not in book]

This question relates to the train both scenario.

The figure below shows an incorrect Hierarchical Task Analysis for the task of catching a train using the train booth described in the Train Booth Example.

  1. List any errors/omissions. (Note tasks 1, 3 and 4 are deliberately not expanded to focus on use of train booth)
  2. Fix the errors/omissions found

incomplete HTA

answer available for tutors only

  1. Missing Plan 2.
    Task 2.1.1.1.1 should be a sub-task of 2.1.1 in sequence after 2.1.1.1; this is an example of sub-task / sequence confusion.
    We have a 'remove' action for the Gold Card but no corresponding 'insert'.
  2. Corrected diagram (indicative) below.
    And plans (indicative):
       Plan 2.
          do 2.1 – 2.2 – 2.3 – 2.4
       Plan 2.2
          do 2.2.1 – 2.2.2
       Plan 2.2.1
          do 2.2.1.1 – 2.2.1.2
       Plan 2.3
          do 2.3.1
          if OK do 2.3.2, 2.3.3

revised HTA


Other exercises in this chapter

ex.15.1 (ans), ex.15.2 (ans), ex.15.3 (ans), ex.15.4 (ans), ex.15.5 (ans), ex.15.6 (tut), ex.15.7 (open), ex.15.8 (open), ex.15.9 (tut), ex.15.10 (tut), ex.15.11 (tut)

all exercises for this chapter


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