Context of Use (Based on Ch2 of Usability-Centered Development) Jim Carter USERLab University of Saskatchewan © Jim A Carter Jr 2012

Usability Usability 1 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 :1998 Guidance on usability CMPT 480/840Context of use 2

Accessibility ISO and ISO 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 :2008 Ergonomics of Human-System Interactions – Accessibility guidelines for information/communication technology (ICT) equipment and services 3. ISO :2008 Ergonomics of Human-System Interactions – Guidance on software accessibility CMPT 480/840Context 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 :2007 and ISO :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 480/840Context of use 4

The Universal Access Reference Model (UARM) CMPT 480/840Context of use 5

UARM & Overlapping Contexts CMPT 480/840Context of use 6

in a specified context of use ISO 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 ) 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 1. ISO/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 480/840Context of use 7

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 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 480/840Context of use 8

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 definition of CoU focuses on tasks rather than on goals ISO/IEC and consider both goals and tasks as parts of the CoU Remember, ISO defines Goal as intended outcome Task as activities required to achieve a goal The CoU needs to tie these two together. CMPT 480/840Context of use 9

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 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 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 480/840Context 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 nor ISO/IEC 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 480/840Context 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 480/840Context 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 480/840Context 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 480/840Context 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 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 480/840Context of use 15