Usability and user Experience

What is usability?

Usability means making products and systems easier to use, and matching them more closely to user needs and requirements.

The international standard, ISO 9241-11, provides guidance on usability and defines it as:

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.

Usability is about:

• Effectiveness - can users complete tasks, achieve goals with the product, i.e. do what they want to do?
• Efficiency - how much effort do users require to do this? (Often measured in time)
• Satisfaction – what do users think about the products ease of use?
• ….which are affected by:
• The users - who is using the product? e.g. are they highly trained and experienced users, or novices?
• Their goals - what are the users trying to do with the product - does it support what they want to do with it?
• The usage situation (or 'context of use') - where and how is the product being used?

Usability should not be confused with 'functionality', however, as this is purely concerned with the functions and features of the product and has no bearing on whether users are able to use them or not. Increased functionality does not mean improved usability.

Usability goals

• Effective to use
• Efficient to use
• Safe to use
• Have good utility
• Easy to learn
• Easy to remember 
• how to use

User experience goals

• satisfying
• enjoyable
• engaging
• pleasurable
• exciting
• entertaining 
• helpful

Evaluation

What, Why & When to evaluate 

What to evaluate:

iterative design and evaluation is a continuous process that examines: early ideas for a conceptual model, early prototypes of the new system, later, more complete prototypes Designers need to check that they understand user's requirements

Why evaluate:

• because user experience can be extremely important for product's success
• because the cycle of design and testing is only validate methodology in existence that    will consistently produce successful results

When to evaluate:

• when it's brand new: develop markups os the product to elicit reactions form the potential users
• upgrades: compare user performance & attitude w/ previous versions

Evaluation Techniques:

Observing users

• Can help identity needs, which can lead to new products
• can help evaluate prototypes
• ways in which to record observations: notes, audio, video, interaction logs
• challenges: how can we observe others without disturbing them? how will analyse the data gather

Asking users their opinions

• Techniques: Interviews and Questionnaires
• Asking experts their opinions is inexpensive and quick

Testing users' performance

• ways to measure user performance to compare 2 or more designs 
•  modeling users' task performance to predict the efficiency and problem of a user interface
• some of these techniques: GOMS and the keystroke model.

Approaches to evaluation

Field studies

• Done in natural settings
• Understanding what people do naturally
• Understanding how products mediate their activities

Usability testing

• Quantifying user performance
• Measuring typical users performing typical tasks
• Recording number of errors, type of errors, task completion time
• User satisfaction

Analytical Evaluations

• Inspections, e.g. Heuristic evaluations, walkthroughs
• Theoretical models to predict user performance

Usability testing

Usability testing is a technique used in user-centered interaction design to evaluate a product by testing it on users. This can be seen as an irreplaceable usability practice, since it gives direct input on how real users use the system. This is in contrast with usability inspection methods where experts use different methods to evaluate a user interface without involving users.

Data gathering techniques

Interviews

• forum for talking to people 
• can be structured, unstructured, or semi-structured
• props, scenarios of use, prototypes can be used 
• good for exploring issues 
• can be time consuming, infeasible to visit everyone

Workshops / Focus Groups

• group interviews
• good at gaining a consensus view and / or highlighting areas of conflict

Questionnaires

• elicit specific information
• can be YES / NO, multiple choice, comment
• often used with other techniques
• can give quantitative / qualitative data
• good for answering specific questions from a large, dispersed group of people