In usability club we don’t say ‘user friendly’ we say ‘USABLE’
To claim that an interface is ‘user friendly’ is subjective and not testable.
To claim that an interface is USABLE requires that we measure ‘usability’ with some predetermined metrics/measures.
This is much more scientific (and legally sound too)
The p rinciples of usable design suggest that there are more specific concepts that can be measured. We need to ensure that our ‘measuring method’ is appropriate to the purpose of the interface or application that we are testing. Even so, “usability” is a very general concept…
Which measuring concept would be most important for the following?
A Playstation game
A data entry screen for a call centre worker – capturing caller name / address details.
A media player in a mobile phone
Bank ATM machine
Note: effectiveness is essential for all of these…
Usability Metrics: Task completion Number of errors made Time taken Number of times frustration is expressed Ratio of optimum click path to actual click path in a website (e.g. navigation should take 2 clicks but user completed task in 11 clicks. Many others
“ The lack of usability of software and the poor design of programs are the secret shame of the [software] industry. … Computing professionals themselves should take responsibility for creating a positive user experience. Perhaps the most important conceptual move to be taken is to recognize the critical role of design, as a counterpoint to programming, in the creation of computer artifacts.”
Mitch Kapor in ‘Bringing Design to Software’ (Edited by Terry Winograd)
Companies in the global software industry are finding it increasingly difficult to compete on functionality or price.
Functionality: With the exception of Patents (which have always been shaky vehicles for competitive advantage in the software industry) Many vendors can offer similar products.
Price: The globalisation of the industry has meant that price levels for similar products has started to equalise (interesting case of Linux / open source)
In the absence of competition at the levels of functionality and price – vendors start to compete at the level of ‘non-functional’ features such as Usability, aesthetics or lifestyle appeal (Think about Apple…)
The Economic Case: Example E-Commerce Usable Websites: Increase likelihood of customers completing a transaction online Customers who can find what they're looking for easily and quickly will be more likely to conduct a transaction Increase customer retention and satisfaction. Ease of use also builds customer loyalty and thus greater profits over time Reduce the costs associated with support, documentation, and training. A usable site will mean that less (telephone) support or documentation and training is required.
The Competitive Case Unlike ‘real-world’ shopping, where switching between suppliers is a matter of considerable effort, in e-commerce: Competitive sites are just a few clicks away - for a customer who is having a negative experience with a site. Customer experience is a key differentiator for business-to-consumer (B2C) websites. Research shows that a negative experience with an e-commerce site means the loss of an individual customer forever (Every, Goodhead 2003)
The Legal and Ethical case DDA – Disability discrimination Act (UK) – originally introduced to promote ‘physical’ access to buildings is being revised (partly by case law, partly by legislation) to include access to electronic or ‘virtual’ resources. Being locked out of a bookstore because it does not have wheelchair access is increasingly equated to being ‘locked’ out of a ‘virtual bookstore’ because it does not provide basic facilities for accessibility software such as screen readers. However, there is also a more fundamental professional and ethical dimension than the purely legal one: Poor accessibility and usability is simply not polite
Cost of usability According to a variety of sources (Nielsen, Usable.net) usability has a cost-benefit ratio of anywhere from 1:10 - 1:100. That is, for every Pound spent on implementing usability the site owner will realise a benefit between £10 and £100 in increased sales.
Constraints on implementing Usability Design Inertia Standards and traditions ‘enshrine’ design approaches and objects – making it very difficult to ‘revolutionise’ design on the basis of usability. (the costs are too great, the staff are already trained in the ‘old system’) Example: The QWERTY keyboard.