Context of Use

(Based on Ch2 of Usability-Centered Development)

Jim CarterUSERLabUniversity of Saskatchewan© Jim A Carter Jr 2012

Usability

Usability1 is the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use

1. ISO 9241-11:1998 Guidance on usability

CMPT 480/840 Context of use 2

Accessibility

ISO 9241-20 and ISO 9241-171 define accessibility as: usability of a product, service, environment or facility by people within the widest range of capabilities

1. ISO TS 16071:2002 Ergonomics of Human-System Interactions – Guidance on accessibility for human-computer interfaces

2. ISO 9241-20:2008 Ergonomics of Human-System Interactions – Accessibility guidelines for information/communication technology (ICT) equipment and services

3. ISO 9241-171:2008 Ergonomics of Human-System Interactions – Guidance on software accessibility

CMPT 480/840 Context of use 3

Accessibility

ISO/IEC JTC1 Information Technology /SC35 User Interfaces in 2011 resolved

“ISO/IEC JTC 1/SC 35 strongly supports the existing definition of accessibility, as specified in ISO 9241-20:2007 and ISO 9241-171:2007

“But., if (for whatever reason) a definition of accessibility is required that is not based upon usability, it should read as follows:

extent to which products, systems, services, environments and facilities can be used by people from populations with the widest range of user needs for the widest range of goals in the widest range of contexts of use

NOTE 1: Contexts of use include direct use or use supported by assistive technologies.

NOTE 2: While it is valid to claim compliance with accessibility standards, it is not appropriate to claim that something is accessible without specifying the user needs, goals, and contexts of use for which it is accessible.

CMPT 480/840 Context of use 4

The Universal Access Reference Model (UARM)

CMPT 480/840 Context of use 5

UARM & Overlapping Contexts

CMPT 480/840 Context of use 6

Context of use

in a specified context of use ISO 9241-11 defines context of use (CoU) as

users, tasks, equipment (hardware, software and materials), and the physical and social environments in which a product is used

Like any shopping list, additions have been suggested: Goals (in ISO/IEC 250631) Content (by ISO TC159/SC4/WG9) Organizational environments / contexts (by both of the above)

We can reword “in a specified context of use” to be: in a specified (set of) users, goals, tasks, equipment (hardware, software and

materials), content and the physical , organizational and social environments in which the product is used

lISO/IEC DIS 25063:2011 Systems and software engineering - Software product Quality Requirements and Evaluation (SQuaRE) - Common Industry Format (CIF) for usability: Context of use description

CMPT 480/840 Context of use 7

Context of use

in a specified (set of) users, goals, tasks, equipment (hardware, software and materials), content and the physical , organizational and social environments in which the product is used Even if we are not evaluating usability for these specified

users they still exist in the CoU and the other specified users might interact with them so we need to consider how their existence might effect usability

This provides further reason to consider stakeholders, as well as “users” Stakeholders are included in the ISO/IEC 250601 discussion of context of use

Usability does not exist in a vacuum. Usability tests in a sterile lab generally miss at least some elements of the CoU

1. ISO/IEC TR 25060:2010 Systems and software engineering - Software product Quality Requirements and Evaluation (SQuaRE) - Common Industry Format (CIF) for usability: General Framework for Usability-related Information

CMPT 480/840 Context of use 8

Context of use

in a specified (set of) users, goals, tasks, equipment (hardware, software and materials), content and the physical , organizational and social environments in which the product is used The ISO 9241-11 definition of CoU focuses on tasks rather

than on goals

ISO/IEC 25060 and 25063 consider both goals and tasks as parts of the CoU

Remember, ISO 9241-11 defines Goal as intended outcome Task as activities required to achieve a goal

The CoU needs to tie these two together.

CMPT 480/840 Context of use 9

Context of use

in a specified (set of) users, goals, tasks, equipment (hardware, software and materials), content and the physical , organizational and social environments in which the product is used ISO 9241-11 seems to be considering this the “systems”

context of the “product” for which usability is being evaluated NOTE: this clumsy wording is an artifact of the time in which this definition was

developed.

ISO/IEC 25063 refers to this as the “technical environment”

So we can further reword this clause to be: in a specified (set of) users, goals, tasks, content and the technical, physical ,

organizational and social environments in which the product is used

CMPT 480/840 Context of use 10

Context of use

in a specified (set of) users, goals, tasks, content and the technical, physical , organizational and social environments in which the product is used Neither ISO 9241-11 nor ISO/IEC 25063 consider content as

part of the CoU

However, the operations and usability of many IT systems can be highly dependent on differences in information content.

Whenever differences in content leads to different contexts that further lead to different levels of usability

then it is important to consider this within the CoU by treating separately each set of content

that might produce different levels of usability

CMPT 480/840 Context of use 11

Context of use

in a specified (set of) users, goals, tasks, content and the technical, physical , organizational and social environments in which the product is used This recognizes the many possible effects of various

environmental factors on usability

Wherever differences in environments lead to different levels of usability

then it is important to consider this within the CoU by treating separately each set of environments

that produce different levels of usability

NOTE: There is a difference between mobile (so called ubiquitous) environments and office and/or home environments. The term ubiquitous should not be used as an excuse to ignore specific environments that produce different levels of usability.

CMPT 480/840 Context of use 12

Context of use

in a specified (set of) users, goals, tasks, content and the technical, physical , organizational and social environments in which the product is used The overall CoU consists of all of the users, goals, tasks,

content and the technical, physical , organizational and social environments in which the product is used

This might actually represent many specific CoU which contain unique combinations of some of the users, goals, tasks, content and the technical, physical , organizational and social environments in which the product is used

CMPT 480/840 Context of use 13

Context of use

in a specified (set of) users, goals, tasks, content and the technical, physical , organizational and social environments in which the product is used There are a variety of different CoU to consider:

There might be different specific CoU within the overall CoU that should be considered separately, because they have different levels of usability

The current CoU is the only one we can be certain of (but it will change)

Changes (to any components of the CoU) will result in a future CoU

We can treat the future CoU in various ways, including: Pretending that it won’t change from the current CoU (not a good idea) Predicting an anticipated CoU that might result from changes to the system, users,

environments, and/or goals and tasks (a better idea) Intentionally planning a designed CoU as part of our development efforts (the best idea)

And each will have its own set of usability measures (usability profile)

CMPT 480/840 Context of use 14

Usability Profiles

By considering the many different CoU that could result in different usability we see that there are very many usability measures that

could, and perhaps should, be considered

ISO 9241-11 does not require us to evaluate and apply all of these possible measures

but it does alert us to the complexity of the problem

It states, “The choice of measures and the level of detail of each measure, is

dependent on the objectives of the parties involved in the measurement “The relative importance of each measure to the goals should be

considered”

CMPT 480/840 Context of use 15