1. Task analysis Chapter 5

2. By the end of this chapter you should be able to... Describe HTA and its features Explain the purpose of task analysis and modelling Distinguish between different types of task analysis Carry out an HTA on an existing system Explain and show how the results of an HTA can be used to improve the usability of a proposed interactive system

3. 5.2 Task analysis Result –Description of tasks that users do when they interact with a system Aim –Find out what the old system enables users to do Focus –Goals and actions (procedures and methods) that users carry out –What users know about their work and tasks –Psychological processes such as perception and memory –Objects and entities on which users act –Relationship between objects and attributes TA should inform, not constrain development of new system TA very useful for “walk-up-and-use” systems –Don’t want to train users –System should be as natural as possible

4. 5.3 What is task analysis? Means of analysing and describing the jobs people do –Provides both method and notation Focus on –peoples’ goals and the actions they carry out –things people know (skills and abilities) –the things they act on

5. 5.4 Purposes of task analysis Purpose –Help designers to understand existing systems, tasks and skills required in people’s existing jobs. Advantage –Contributes to better understanding of users’ requirements Evaluation of existing system –Assists in design of new system –Triggers insights of how to do the task better Notation –Simple and descriptive –Should cover both tasks and the users

6. 5.5 Approaches to TA Not all tasks structures are hierarchical  HTA not always applicable Several approaches –HTA –Procedural –Knowledge-based (KB) –Entity-relationship (ER) Procedural TA –All activities are executed step-by-step, linear and sequential –Directional flow with a start and end –Preceding task must be completed before commencing with next one –Represented in flowchart diagram

7. 5.5.1 Inputs to and outputs of TA Inputs –Problem statement –Observation of existing systems –Analysis of users Outputs –HTA or other document, e.g. matrix –Problem statement –Observations of existing system Good and bad points –Analysis and profile of the user population Issues –Who are the users? –How diverse is the user population? –How to provide universal access? –Why don’t people use the system? –Observe goals as well as tasks

8. 5.5.2 Data collection Ask people –Assume that they have adequate insight –May not always tell the truth Observe users working –Users might be nervous, not acting naturally –Users might be conscious not to make mistakes –Users might show only subset of tasks that they know well Talk to users informally, in focus groups or interviews Read available documentation or training material Do the task yourself Familiarise yourself with existing systems Analyse real tasks, i.e. don’t set up tasks superficially Develop abstractions of real tasks Conduct experiments Ethnographic methods, social probes, surveys Contextual enquiries

9. 5.6 Hierarchical Task Analysis One of the most common forms of TA Involves –Identifying goals that user wants to achieve –Decomposing goals into tasks –Further decomposing into subtasks –Repeat; stop at the level of actions

10. 5.6.1 HTA example 1: Withdraw cash from ATM 0 Withdraw cash 1 Check machine will work 1.1 Look at status indicator 1.2Look for card logo 2 Insert card 3Enter PIN number 4Select Language 5Initiate withdrawal transaction 5.1Select withdraw cash 5.2Specify account 5.3 Enter amount 6Complete transaction 6.1Take card 6.2 Take cash 6.3 Take statement

11. 5.6.2 Adding plans Hierarchical diagram / text specifies which subtasks are part of a task Does not specify how the subtasks are carried out Plans are used to describe –how sub-tasks are combined –order of subtasks –conditional or optional subtasks –optimum way of using sub-tasks –any repetition required or involved HTA not complete without complete set of plans to guide implementation of sub-tasks ATM example –Next slide

12. Plan 0: do 1; if possible do 2; repeat 3 until PIN correctly entered; do 4; do 5; do 6. Plan 1: do 1.1, 1.2 in any order Plan 5: do 5.1; do 5.2; do 5.3. Plan 6:wait until card available; do 6.1; wait until cash available; do 6.2; wait until statement available; do 6.3. 0 Withdraw cash 1Check machine will work 1.1 Look at status indicator 1.2Look for card logo 2Insert card 3Enter PIN number 4Select Language 5Initiate withdrawal transaction 5.1Select withdraw cash 5.2 Specify account 5.3 Enter amount 6 Complete transaction 6.1Take card 6.2Take cash 6.3Take statement 5.6.2 HTA example: Plans added

13. E2: Example 2 The manual task of filing documents in a filing cabinet... –You have an unsorted stack of documents –Your filing cabinet contains folders that are ordered somehow –How do you get all the documents into the correct folder?

14. E2/T0: Filing cabinet 0. Store documents in filing cabinet 1.File lots of documents 2.File one or two documents Plan 0:Do 1 or 2

15. E2/T2: Filing one or two things Simply find the appropriate folder and put the documents in... 2.File one or two documents 2.1.Open cabinet 2.2.File each document 2.3.Close cabinet Plan 2:Do 2.1., (2.2. repeatedly) then 2.3.

16. E2/T2.2: Filing each document 2.2.File each document 2.2.1.Find appropriate file 2.2.2.Open file 2.2.3.Place document in file 2.2.4.Close file Plan 2.2:Do 2.2.1, 2.2.2., 2.2.3., then 2.2.4.

17. E2/T1: Filing lots of documents Strategy Sort the documents into order first then split the sorted documents up into ‘categories’ (ie all the documents whose author begins with ‘A’) then work through the filing cabinet, putting each category into the right file 1.File lots of documents 1.1.Choose criteria on which documents are sorted 1.2.Sort all documents to be filed into order 1.3.Split documents up into categories 1.4.Open cabinet 1.5.Place each category of document into file 1.6.Close cabinet Plan 1: Do 1.1., 1.2., 1.3., 1.4., (1.5. repeatedly) then 1.6.

18. E2/T1.1: Choosing sorting criteria 1.1.Choose criteria on which documents are sorted 1.1.1.Choose alphabetical by title of document 1.1.2.Choose alphabetical by author of document 1.1.3.Choose date order Plan 1.1:Do any one of 1.1.1., 1.1.2., or 1.1.3.

19. E2/T1.5: Placing categories in files 1.5.Place each category of document into file 1.5.1.Open file 1.5.2.Place each document in file 1.5.3.Close file Plan 1.5: Do 1.5.1., (1.5.2. repeatedly) then 1.5.3.

20. HTA: E2 0. Store documents in filing cabinet 1.File lots of documents 1.1.Choose criteria on which documents are sorted 1.2.Sort all documents to be filed into order 1.3.Split documents up into categories 1.4.Open cabinet 1.5.Place each category of document into file 1.6.Close cabinet 2.File one or two documents 2.1. Open cabinet 2.2. File each document 2.2.1.Find appropriate file 2.2.2.Open file 2.2.3.Place document in file 2.2.4.Close file 2.3. Close cabinet Plan 0: Do 1 or 2 Plan 1: Do 1.1., 1.2., 1.3., 1.4., (1.5. repeatedly) then 1.6. Plan 2: Do 2.1., (2.2. repeatedly) then 2.3. Plan 2.2: Do 2.2.1, 2.2.2., 2.2.3., then 2.2.4.

21. E2: Things to note... Note … –The overall task is numbered 0 –The tasks are all described by verbs –Each task that is decomposed must have a plan to go with it –Plan X must only refer to sub-tasks to X Think about … –Imagine that you are designing an electronic filing system –What does this HTA tell you about filing systems? –Which bits of the manual task would you keep, and which would you do away with or redesign? –Why?

22. E3. Example Jill creates a stack of new catalogues in a corner of her kitchen. When she is preparing dinner, she can flip through a catalogue to see what’s new or on sale or what strikes her interest. In the evening she may pick out five or six catalogues to look at while the family is watching TV. She may even take a few to bed, or to the bath. Generally she simply browses through pictures, reading descriptions only when the pictures look interesting. When she finds something interesting she may dog-ear the page, draw a circle round it or mark the page with a sticky note. She keeps catalogues with marked pictures around until she wants to make a purchase.

23. E3/T0: Example 0.Using catalogues 1.Browse items 2.Mark items Plan 0: do 1 then 2 if item found

24. E3/T1: Example 0.Using catalogues 1.Browse items 1.1.Browse by what’s new 1.2.Browse by sales 1.3.Browse by items that interest 1.4.Browse by catalogues 1.4.1.Browse in kitchen 1.4.2.Browse while watching TV 1.4.3.Browse in bed 1.4.4Browse in bath 2.Mark items Plan 1: do 1.1 or 1.2 or 1.3 or 1.4

25. E3/T2: Example 0.Using catalogues 1.Browse items 2.Mark items 2.1.Circle item 2.2.Mark page 2.2.1.Dog-ear page 2.2.2.Sticky on page Plan 2: do 2.1 or 2.2

26. E3/T2: Example 0.Using catalogues 1.Browse items 2.Mark items 2.1.Circle item 2.2.Mark page 2.2.1.Dog-ear page 2.2.2.Sticky on page Plan 2.2: do 2.1.1 or 2.2.2

27. 5.6.5 Key features interactive system based on HTA Flexibility Interactivity Portability (Location and hardware) Flexible browsing capability Suitable functionality These are passed as requirements to the design cycle

28. Summary Task analysis gives designers a means of describing how people do their jobs Serves different purposes in design and development