User and Task Analysis Howell Istance Department of Computer Science De Montfort University

SOFT Interactive Systems Objectives...

SOFT Interactive Systems User Centered Design Process

SOFT Interactive Systems System Related User Characteristics n What characteristics can you expect of the users of your interface? u frequency of use u discretion to use the system u knowledge of the task which the system will support u knowledge of computers u experience of other similar systems u general abilities, e.g. literacy, vision u attitude towards computers (and your system) u existing skills (keyboard, mouse)

SOFT Interactive Systems Three-Dimensional Framework n Three Dimensional Framework for User Classification Knowledge of Computers Knowledge of Task Frequency of Use (low)(high)

SOFT Interactive Systems Design implications n Provide for high degree of sophistication in interface: u range of functions provided, u flexibility to combine functions to provide new commands, u possibilities to customise interface to own needs. n Lower requirement for user support than with other user types. n Can utilise programming languages and extensible command languages (e.g. macros and scripts). Computer professionals

SOFT Interactive Systems Highly variable group in terms of knowledge and experience Design implications n Important to support the user ‘guessing’ or experimenting with how operations can be carried out at the interface. Consistency and a close match to the user’s task model is important. n Frequency of use determines how much the user can be expected to learn short cuts and accelerators. n User support provided by the interface is important. Professionals without programming experience

SOFT Interactive Systems Design implications n Can anticipate significant learning of routine operations to take place, so can make use of abbreviations and codes for data input. n Can expect strong user skills to be developed, such as keyboard skills. n Error messages must be clear and provide specific guidance for recovery. n Cannot expect users to develop deeper knowledge or understanding of the computer system without specific training. Skilled clerks

SOFT Interactive Systems Design implications n Every type of user error must be trapped. This type of user will not be able to infer what is happening or the cause of an error condition. n Require explicit on-screen prompts for each step of the dialogue. n High degree of user support and a low degree of sophistication is required in the interface. ? Naïve users

SOFT Interactive Systems Task Analysis n provides an essential basis for u early stages of interface design u evaluation of design at early and late stages u structuring training in system use u structuring and design of documentation

SOFT Interactive Systems Levels of Task Analysis n relate to existing situation or new system. General Analysis of User Characteristics Detailed Analysis of tasks in present job(s) Subset of tasks to be included in new system Analysis of Actions and Objects in new system

SOFT Interactive Systems General Analysis level n who are the users u classify the users into one or more groups u define characteristics of the group n what are the main task components of the users present job u what proportion of time is spent in different tasks u what causes variations in this n where are the tasks carried out n what equipment (other than the computer system) are used n what communication is there between the user and other people

SOFT Interactive Systems Detailed analysis of tasks in present job n what is the hierarchical structure of main tasks, and subtasks within these main tasks n how do users see the structure of their job in terms of tasks n for each task identified u what information is required u what actions arise or result from decisions u what feedback is provided on effect of actions u what affects successful performance u what are the possible errors and what factors cause these

SOFT Interactive Systems Detailed analysis of tasks in present job n what are the good features of the existing system which should be retained in the subsequent redesign n what are the bad features of the existing system that should be designed out n what skills are required for each task n how are the required skills trained initially and how are these retained

SOFT Interactive Systems Actions and Objects n Low level (down the hierarchy) task descriptions can be formulated as actions performed on task-related objects u e.g... change start time of appointment u object: appointment u attribute: start time u action: change/edit n a dictionary of objects, attributes and associated actions can be constructed through process of u rationalisation u generification

SOFT Interactive Systems Building an object dictionary n interviews with users provide textual descriptions of tasks n these can be analysed by identifying u nouns (candidate objects) u verbs (candidate actions) n process of generification to identify what are essentially descriptions of the same thing n process of hierarchy building to identify objects as members of related classes

SOFT Interactive Systems Objectives of task analysis to support interface design n identify a hierarchy of user goals, tasks and subtasks together with a plan describing how and when these are done n represent lowest level task as a set of procedures (using something like pseudocode) u include statements of information requirements and exception conditions n identify set of actions and associated objects

SOFT Interactive Systems Hierarchical task analysis (HTA) Originally devised to define training requirements in process industry - method needs additionally u descriptions of information requirements for lowest level sub- operations u dictionary of objects and associated actions Representation u tree diagram or tabular format Advantages of HTA u simple, informal notation u but still requires considerable skills on part of analyst.

SOFT Interactive Systems Example of HTA Delete block of text in a word processor 1.Delete block of text Goal

SOFT Interactive Systems Example of HTA Delete block of text in a word processor 1.Delete block of text Goal 2) Select 'cut' from Edit menu 1) Select block of text or 2) Select cut icon from toolbar or 2) Press 'delete' key then Tasks

SOFT Interactive Systems HTA representation 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar

SOFT Interactive Systems HTA representation 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar Plan 1: 1-2 or 1-3 or 1-4

SOFT Interactive Systems HTA representation 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar Plan 1: 1-2 or 1-3 or 1-4 1) Anchor the start of the block 2) adjust the extent of the block 3) Anchor end of the block then Subtasks

SOFT Interactive Systems HTA representation of tasks and subtasks 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar 1.Define start of text selection 2. Adjust length of text selection 3. Define end of text selection Plan 1: 1-2 or 1-3 or 1-4 Plan:

SOFT Interactive Systems HTA representation of tasks and subtasks 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar 1.Define start of text selection 2. Adjust length of text selection 3. Define end of text selection Plan 1: 1-2 or 1-3 or 1-4 Plan: Procedure 1) position text insertion in front of first character of block 2)...

SOFT Interactive Systems How far to decompose tasks? 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar 1.Define start of text selection 2. Adjust length of text selection 3. Define end of text selection Plan 1: 1-2 or 1-3 or 1-4 Plan:

SOFT Interactive Systems How far to decompose tasks? 1.Delete block of text 1. Select text block 2. Press ‘delete’ 3. Select cut from edit menu 4. Select cut icon from toolbar 1.Define start of text selection 2. Adjust length of text selection 3. Define end of text selection Plan 1: 1-2 or 1-3 or 1-4 Plan: as far as is useful for the analysis

SOFT Interactive Systems Means of collecting task analysis data n interviews with potential users n observations of users performing tasks by trained observers n activity sampling n activity logging (by observer) n activity logging (by user) - 'diary of activities'