Accessibility and Usability Definitions

(a)Accessibility is concerned with removing any barriers that may otherwise hinder some people from accessing the system (b)Usability is concerned with the quality of interaction in terms parameters such as the time taken to finish a task,errors made,time to be a competent user (c)Acceptibility is concerned with fitness to purpose.This covers personal preferences which lead to people talking to an artifact,or not

1.Physically-Inappropriate sitting of equipment or input an output devices that make excessive demands on their abilities 2.Conceptually-A user can not understand complicated instructions,obscure commands or cannot form a clear mental model of the system 3.Economically-Users cannot afford essential technology 4.Cultural exclusion-This results from the designer making inappropriate assumptions about the way people behave and carry out their lives 5.Social exlusion-Due to unavailability of equipment at a required time or place.Having to be part of a particular social group to understand certain messages or behaviours

Design for all(Universal design)which goes beyond interactive design principles and uses all design endeavors Inclusive design which caters for all humans.Accesses problems early and designing to accomodate people with disasibilities inturn making the design better for everyone

Varying abilities is a common characteristic of humanity.We change physically and conceptually throughtout our lives In any part of our lives,our self esteem,identity and wellbeing id affected by our ability to function in our physical surroundings with a sense of comfort,independence and control 3.Usability and aesthetics are both mutually compatible 4.There is a more realistic approach that argues that the will be often reasons(technical or financial)that prove inclusion as unattainable

Equitable use-The design does not disadvantage or discriminate any group of people Flexibility in use-The design accomodates all individual preferences and interests Simple,intuitive use-The design is easy to use and understand regardless of the user's experience,knowledge and level of concentration Tolerance for error-The system must minimize the hazards and adverse consequences of actions particularly mistakes and errors Perceptible information-Must deliver information effectively,regardless of the user's ambient surrounding and sensory abilities Low physical effort-Can be used efficiently and comfortably with minimum fatigue Size and space to approach-There must be appropriate space and size to approach,manipulationan and use regardless of the user's body size,posture and mobility

The designer should include special needs users in the requirements analysis and testing of existing systems Designer should consider whether new technology features affect special needs users negatively or positively and take note of this specification

Effecient-users will be able to do things in an efficient amount of effort Effective-contains appropriate instructions and functions in a well organized manner East to learn-Easy to learn how things are done and still remember how to do them after a while Safe to operate-In all contexts that will be used High utility-In that it does the things that people want to get done

the gulfs People have goals and yet devices are all about simple actions the gulf of execution-concerned with transforming actions into goals the gulf of evaluation-concerned with checking whether the action is bringing the person towards the goal the two gulfs have to be bridged both semantically(does the person know what to do and what has happened)and physically(can the person physically and perceptually find out what to do and what has happened?)

focus on people and tasks-the designer first needs to know who the users are ,in part by studying what work will be accomplished,in part by making the users part of the design team through interactive design or consultants Emperical measurement-Early in the development process,the intended user's reactions or actions are observed,recorded and analysed and they should be made the prototype for the design work Iterative design-When issues are found in the design,they must be fixed.This means that the design might be iterative:Design cycle,test and measurements,redesign will be repeated as often as neccessary no matter how good the designer is they cannot et it right on the first try intergrative usability-all usability factors must evovle around one another

Political-What is the system?Do people trust it?In many organisations technology is created mainly for economic purposes.This might neglect the peoples right in broader environments Social and cultural habits-Social habits are concerned with what people want to do and cultural habits are all about color,symbolism,iconography and language of people Economic-Many economic issues render tech useful or not.Does tech offer value for money?Intro to new technologies may hinder how businesses work and make money.Norman characterises this as a 3 legged stool,Experience,Marketing,Technology Convenience-Ensuring the peoduct is functional ,meets the needs of users and includes disables ones