1. Requirements II: Task Analysis

2. Objectives By the end of the class, you will be able to… Write detailed task descriptions to inform design. Create scenarios to demonstrate example uses of a system. Perform hierarchical task analysis.

3. Some tasks Enter meeting details into a paper calendar Arrange a meeting using a shared calendar application Choosing mp3 files to play while driving

4. What characteristics of a task are important to consider? Variability from one time to the next Regularity Knowledge & skills required Physical environment Time critical? Saftey hazards Alone vs. group? Other simultaneous tasks

5. Task Scenarios A personal narrative story identifying a task, with specific details –May make use of a persona –One specific task, not a whole series of tasks Shows context of use Usually does not say anything about the system interface

6. Restaurant guide scenario Christina is at the park with 3 friends. They’ve decided to go out for dinner. Christina uses her mobile device to search for a Japanese restaurant within walking distance (1 km), that will cost less than $15 per person. The system tells her that space is available. She then makes an online reservation for 6 pm.

7. Scenario for shared calendar “Joe enters all the names of the meeting participants together with some constraints such as the length of the meeting, roughly when the meeting needs to take place, and where it needs to take place. The system checks against the individuals’ calendars and the central departmental calendar and presents Joe with a series of dates on which everyone is free all at the same time. Then the meeting is confirmed and written into people’s calendars. Some of Joe’s colleagues want to be asked before the calendar entry is made, so the system emails them automatically and asks that it be confirmed before it is written in.”

8. Use Case Like a scenario, but –Describes interface details –Specific order to subtasks –No personalized details Steps through a task for a given interface Lists all the alternate possibilities (alternate courses)

9. Use case for shared calendar 1. The user chooses the option to arrange a meeting. 2. The system prompts user for the attendees. 3. The user types in a list of names. 4. The system checks that the list is valid. 5. The system prompts the user for constraints. 6. The user types in meeting constraints. 7. The system searches the calendars for a date that satisfies the constraints. 8. The system displays a list of potential dates. 9. The user chooses one of the dates. 10. The system writes the meeting into the calendar. 11. The system emails all the meeting participants informing them of them appointment

10. Alternative courses for shared calendar Some alternative courses: 5.If the list of people is invalid, 5.1System displays an error message. 5.2The system returns to step 2. 8.If no potential dates are found, 8.1The system displays a suitable message. 8.2The system returns to step 5.

11. Scenarios vs. Use cases Scenarios help before you start designing & also for evaluation –Help you clearly define tasks Avoid making assumptions about how interface will operate –Evaluate whether the interface will work for a particular user in a particular instance Use cases help once you have a design –Evaluate whether a design will work for all possible cases (to come: cognitive walkthough technique)

12. Online Grocery Store Activity Part I Define the tasks that people will do with the system Create 3 task scenarios

13. Hierarchical Task Analysis (HTA) Break a task into smaller and smaller subtasks, until you reach the smallest unit of work.

14. HTA for shared calendar Arrange a meeting given a list of participants –Decide meeting constraints Approx time / deadline Location Who will attend –Choose a time for the meeting Check when other participants are available Find times when everyone is free Select one time for the meeting –Record the meeting time and location Type or write into calendar –Notify other participants

15. HTA for shared calendar (con’t) Some of these tasks break down further, e.g.: Check when other participants are available: –For each participant »view their publicly available schedule »Record all free times Find times when everyone is free –For each time that P1 is available »Check whether P2 is free »Record result »Check whether P3 is free »Record result »…

16. Online Grocery Store Activity Part II Do a Hierarchical Task Analysis for one of your scenarios

17. Key Points Define tasks in detail before designing or evaluating Scenarios and use cases provide concrete examples of how your system will be used