Chapter+Twenty

=__**Chapter 20 TASK ANALYSIS**__= =Table of Contents= Chapter 20 TASK ANALYSIS20.1 Goals, Tasks and ActionsGoalsTasks and ActionsTask Analysis Methods20.2 Task Analysis and Systems Design20.3 HTA20.4 GOMS20.5 Structural KnowledgeBACK TO CHAPTER SUMMARIES - looking at the tasks people do or will have to do is necessary to human centre design

__**20.1 Goals, Tasks and Actions**__
task analysis – a specific view of interactive systems design which leads to specific techniques

task – a goal together with some ordered set of actions

detailed definition of task analysis: - work achieved by a work system changing a application domain o application domain or domain is an abstraction of the real world relevant to the work system o work systems in HCI can have one or more human or computer components - tasks are the means by which a work system changes a domain; means by which work is achieved - goals are a desired states of a domain that the system should achieve by the task - system performance is satisfactory when goals are achieved in domain by tasks - task analysis is the study of how work is achieved by tasks

__**Goals**__
Goal – state of domain that a system wishes to achieve; specified at particular levels of abstraction - this definition allow for artificial entities to have goals

agent – people and software systems which actively and autonomously try to achieve some state of domain

technology – physical device, information artifacts, software systems and other methods or procedures

- goal can be achieved in a variety of ways; one way: 1. agent must decide which technology to use to achieve the goal - selection depends on agent’s knowledge of function, structure and purpose of technology 2. once decided tasks can be defined

**__Tasks and Actions__**
Task – structured set of activities required, used, or believed to be necessary by an agent to achieve a goal using a particular technology - can consist of subtasks

subtask – a more detailed level of abstraction

structure (of an activity; plan or method) – includes selecting between alternative actions, performing actions numerous times and sequencing of actions

action – a task which has no problem solving associated with it and does not include any control structure

__**Task Analysis Methods**__
Logic of the task – sequence of steps that need to be undertaken by a work system to achieve a goal

Cognitive task analysis – understanding what cognitive processes the work system will have to undertake to achieve a goal - cognitions include: thinking, problem solving, learning, memory, mental models

- for goals, tasks and actions consider… o procedural knowledge: • goal task mapping: knowing what to do to achieve goal • task action mapping: know how to do it • goal formation stage: first of all, knowing you can achieve a goal o structural knowledge: domain concepts and their interrelation • useful for problem solving

__**20.2 Task Analysis and Systems Design**__
- task analysis will result in a task model o a task model can take various forms

- task analysis techniques and methods involve: o optionally, parallelism or non standard actions o goal of using notation o usability for communication o usability for modeling tasks o adaptability of a task analysis technology to new systems, aims or requirements

- task analysis techniques are usually mono-teleogical

mono-teleogical – the assumption that the agent or system has a single purpose or goal

teleogy – study of purposes, causes and reasons - usually missing from task analysis techniques

- task analysis is undertaken at different times during development for different purposes o during analysis task analysis is concerned with practice of work and function between people and technology o during design and evaluation task analysis is concerned with cognition demanded by a design, the logic and future distribution

- three task analysis techniques: 1. HTA hierarchical task analysis 2. GOMS goals, operators, methods, selection rules; procedural knowledge 3. ERMIA entity relationship modeling of information artifacts; structural knowledge

__**20.3 HTA**__
HTA – graphical representation of a task structure based on a structure chart notation

Structure charts – a sequence of tasks, subtasks and action as a hierarchy and include notational concentions to show whether an action can be repeated a number of times (iteration) and the execution of alternative actions (selection)

Sequence – shown by ordering left to right

- HTA is not easy o Must spend time getting descriptions of tasks and subtasks correctly to be represented hierarchically

//→ Annett’s step by step guide on how to do an HTA: 1. decide on purpose of analysis 2. define task goals 3. data acquisition; how to collect data? 4. Acquire data and draft hierarchical diagram 5. Recheck validity of decomposition with stakeholders 6. Identify significant operation and stop when the effects of failure are no longer significant 7. Generate and test hypotheses concerning factors affecting learning and performance//

- HTA highly effective with helping people to really understand structure tasks

**__20.4 GOMS__**
- most famous and long lasting - focuses on cognitive processes required to achieve goal

goals – what people trying to do using system operators – actions system allows people to make methods – sequences of subtasks and operators selection rules - -rules people use to choose between methods of achieving the same subtask

- this method is applicable only if people know goal - not suitable analytical method where people are problem solving - applicable to single user system interaction - need to describe, organize and structure tasks, subtasks and actions hierarchically

__**20.5 Structural Knowledge**__
- mental model can be used to analyze tasks o two mental spaces: goal and device

goal space – describes the state of the domain that the person is seeking to achieve device space - -describes how technology represents the goal space

- mental map is analogous to real maps and can be used for tasks

ERMIA entity relationship modeling of information artifacts - can represent concepts in peoples minds - relationship between entities annotated with 1 or m (more) - entities represented with boxes, relationships with lines and attributes with circles

- basis of ERMIA → looking for entities and relationships and representing them as diagrams

- key feature use same notation to represent conceptual aspects of a domain and perceptual aspects

- menus have 2 entities (header – item) - relationship of H-I is 1:m because one heading can have many items - TRUE relationship between H-I is m:m because the item can be under many other headings o Very complex relationship and can be replaced with m:1 entity

- ERMIA represents both physical and conceptual aspects of interfaces enabling comparisons and evaluations o Presents clear view of different models can be used for process of reasoning about models - can be used to navigate through information structures to retrieve pieces of information and estimate number of steps to get there

→ //Step by step to developing ERMIA models 1. take some analysis and requirement work drawing up a task begin to sketch perceptual or conceptual interface 2. identify major entities and relations with one another 3. begin to sketch out entities and relationships 4. replace m:m with new m:1 entity 5. iterate and work with the sketch analyzing and identifying more relationships and looking for characteristics of the entities//