1 Unit C-Task Analysis (c) elsaddik SEG 3210 User Interface Design & Implementation Prof. Dr.-Ing. Abdulmotaleb El Saddik University of Ottawa (SITE 5-037) (613) x 6277 site.uottawa.ca mcrlab.uottawa.ca

2 Unit C-Task Analysis (c) elsaddik Unit C : Task Analysis 1.Introduction to Task Analysis 2.Tasks and Goals Revisited 3.Approaches to task analysis 4.A Procedure for task analysis 5.Case Study: File Manipulation on Command Line vs. GUI 6.Mail-Order Case Study: Classes of User

3 Unit C-Task Analysis (c) elsaddik 1. Introduction to Task Analysis Definitions of task analysis: The process of analyzing and improving the way people perform their jobs What people do  The things they do What things they work with  The things they act on What they must know  The things they need to know Provides an essential basis for Early stages of interface design Evaluation of design at early and late stages Structuring training in system use Structuring and design of documentation

4 Unit C-Task Analysis (c) elsaddik Example TASK: Clean the house In order to clean the house you need to Get the vacuum cleaner out Fix the appropriate attachments Clean the rooms When the dust bag gets full, empty it Put the vacuum cleaner and tools away You must know about: Vacuum cleaners, their attachments, dust bags Cupboards in which the vacuum cleaner is kept rooms to be cleaned, … etc.

5 Unit C-Task Analysis (c) elsaddik 2. Tasks and Goals Revisited Goals and tasks are sometimes equated We will separate them What is a task? A procedure Performed by one or more classes of user Directed towards a goal May have a super-task Broken down into subtasks With possible loops and alternation (if-then) Involves actions (at the bottom level) A task that involves no problem solving and cannot be usefully broken down into components  Avoid thinking of a task in terms of what the computer alone must do

6 Unit C-Task Analysis (c) elsaddik 2. Tasks and Goals Revisited What is a goal? A state the user wants to be in Achieved by performing a task Sub-goals are the goals of subtasks The user has to figure out what task to perform May or may not be explicitly known in advance of task execution e.g. Implicit goal: Writing a letter general task is known details evolve goal is achieved when user is satisfied e.g. Explicit goal: Adding an item to inventory task and goal are known by an experienced user  High level goals are less likely to be explicit Other perspectives: A goal is often equated with its task

7 Unit C-Task Analysis (c) elsaddik 3. Approaches to task analysis Task decomposition Splitting task into (ordered) subtasks The order in which these are performed Knowledge based techniques What the user knows about the objects and actions involved in a task and how that knowledge is organised Focus on: Objects - used in task Actions - performed Taxonomies represent levels of abstraction Entity-relation based analysis Relationships between objects, actions and the people who perform them General method: Observe Collect unstructured lists of words and actions Organize using notation or diagrams

8 Unit C-Task Analysis (c) elsaddik 4. A Procedure for Task Analysis (case studies are found in subsequent sections) Two basic steps: 1.Model tasks 2.Simplify and improve each task model Use the simplified task model as a basis for the user interface.

9 Unit C-Task Analysis (c) elsaddik Model tasks (easier if there is an existing system) Observe and interview users … and/or brainstorm … and/or prototype … and/or study documentation a)Determine the classes of users: Manager, salesperson, shipper, client, etc. b) Create a list of all tasks to be performed by users c) Prioritize the tasks by frequency of use and importance Later on, perform more detailed analysis on higher-priority tasks If there is an existing system, one can measure the usage of commands  Note different classes of user will use tasks with different frequencies

Unit C-Task Analysis (c) elsaddik Model tasks d) Gather other detailed information about each task Why? Determine the goals Determine preconditions:... what users need to know to perform the task... what are the data and objects involved (perhaps from a parallel object oriented analysis) How? Decompose the task into subtasks and actions Determine side-effects of performing the task …things changed that are not directly relevant to the goal state Determine users mental models there may be several Determine any interrelationships between tasks Determine possible breakdowns things that can go wrong Iteratively perform this step for subtasks e) Diagram each task Possible techniques: hierarchies of subtasks (probably best) time-lines (scenario diagrams) flow-charts

Unit C-Task Analysis (c) elsaddik Simplify and improve each task model a) Abstract task models as much as possible Determine what the real top level goals are Remove details (lower level subtasks) that can be changed i.e. subtasks that are part of this office environment or user interface situations where different systems would have somewhat different subtasks b) Build or improve conceptual models (discussed later) to help simplify the user’s thinking about tasks c) Add back detailed layers one-by-one Think of several alternative sets of subtasks and determine which is better

Unit C-Task Analysis (c) elsaddik Simplify and improve each task model c) Add back detailed layers one-by-one Use the following guidelines: Standardize subtasks so similar subtasks are performed in similar ways Rearrange the order of subtasks to make them easier to perform Reduce the need for the user to perform subtasks (i.e. reduce overhead) Minimize setup and configuration by using defaults Reduce the need for users to recall from memory Where possible have the computer calculate whatever it can Eliminate subtasks if their benefit is less than their cost Ensure the system guides the user through the tasks The system should ‘know how the user works’ It should help the user set up goals Account for the possibility of multitasking If a user jumps around among tasks ensure steps need not be repeated and that the user can pick up where she left off

Unit C-Task Analysis (c) elsaddik 5. Case Study: File Manipulation on Command Line vs. GUI Goal: Execute a command on a command line that has one or two filename arguments To be performed: frequently by: command-line users (often experts these days) Preconditions: Command verb is known Filenames are known Decomposition: 1.Ensure command prompt is displayed 2.Type command verb 3.Enter first filename 4.Decide: If no second filename, go to step 6 5.Enter second filename 6.Verify command 7.Press

Unit C-Task Analysis (c) elsaddik 5. Case Study: File Manipulation on Command Line vs, GUI Breakdowns: Command verb incorrect Filenames(s) incorrect Wrong number of arguments specified Arguments in wrong order Operation not allowed on filenames

Unit C-Task Analysis (c) elsaddik Goal: Delete a file in DOS To be performed: frequently by: command-line users Preconditions: File to delete is known System is displaying the command prompt Decomposition: 1.Retrieve the command verb for deleting a file,e.g. ‘ERASE’ or ‘DELETE’ 2.Think of directory name and filename 3.Enter the command

Unit C-Task Analysis (c) elsaddik Goal: Delete a file in DOS Analysis to improve task model (Possible real top-level goals): Make space on disk for something else Possible simplification: Automatic compressing / archiving of old files Get rid of unwanted clutter Possible simplification: Build version control into file system so multiple versions do not accumulate Ensure nobody else can read file Other possible simplifications: Eliminate need for recall and typing in step 1 by providing a menu Simplify steps 2 and 3 by providing direct manipulation Have the system prompt the user if the command is entered without the file spec

Unit C-Task Analysis (c) elsaddik Goal: Drag an item to its destination in a GUI desktop To be performed: frequently by: all users Preconditions: Item to drag is known Effect of dropping item on destination is known Decomposition: 1.Locate icon or name of item on screen 2.Move cursor to icon 3.Press and hold mouse button 4.Locate destination on screen 5.Move cursor to destination 6.Verify that destination highlighted 7.Release mouse button Breakdowns: Item to drag is not draggable Cursor not over icon in step 2 Mouse released early or not over destination Destination invalid for item being dragged

Unit C-Task Analysis (c) elsaddik Goal: Delete a file in a GUI desktop To be performed: frequently by: all users Preconditions: File to delete is known Decomposition: 1.Bring file manager to the foreground (how to do this depends on the OS version) 2.Uncover trash/recycle icon if hidden 3.Drag file to the trash/recycle bin User’s mental model: File will be sitting in the trash/recycle bin and can be retrieved Possible simplifications: Provide a keyboard shortcut for step 1 Provide a keyboard shortcut for steps 2 and 3

Unit C-Task Analysis (c) elsaddik 6. Mail-Order Case Study: Classes of User 1.Client rep/salesperson Takes phone orders and queries Needs to be able to work very fast 2.Client Dials in to place orders/queries Needs very simple approach 3.Shipper Assembles orders to be sent to clients when sufficient inventory is present Puts items in crates and sends them to clients Records that items have been sent 4.Return handler Handles returns of merchandise by client

Unit C-Task Analysis (c) elsaddik 6. Mail-Order Case Study: Classes of User 5.Supplier orderer Sends out orders printed by the system in response to client orders and/or low inventory 6.Receiver Matches packages received from suppliers to supplier orders Updates inventory 7.Inventory taker Verifies inventory matches system Adjusts system as necessary, reporting discrepancies. 8.Backorder processor Sends polite letters when delays occur Pursues suppliers so orders can be fulfilled 9.Accounts receivable clerk Updates system when accounts have been paid Pursues derelict clients Sets credit limits 10.Inventory management analyst Decides how much of each item should be kept in inventory 11.Manager Performs general queries