Usability testing
Introduction

“Usability rules the Web.  Simply stated, if the customer can’t find a product, then he or she will not buy it.  The Web is the ultimate customer–empowering environment.  He or she who clicks the mouse gets to decide everything.  It is so easy to go elsewhere; all the competitors in the world are but a mouse click away.”

Jakob Nielsen, 2000

Before any time is spent on designing the perfect usability test, it is important to understand that there are five dimensions to usability.  These include:

1. Learnability – This is essential to all Web sites.  It refers to the time it takes for a user to understand and utilise a Web site.  Users need to be able to understand how a site works and what it offers almost immediately. If they can not, they will leave the site and in most cases, never return.  When considering learnability, a good example is a ticket machine at your local train station, they are designed to be self-explanatory and quick to use. Once used, you generally know which buttons to press on your next visit.
2. Efficiency of use – This concerns the amount of time it takes a user to accomplish a given task on a Web site, and how productive per unit of time the design is.  An example of this could be when calling a large organisation. How efficient is their touch tone option service? Does the list of specialised options reduce the time spent on the line, or does it increase it?
3. Memorability – How memorable is a Web site?  Can users re-acquire their proficiency without having to re-acquaint themselves with the site’s structure? Can a user go directly to things of interest found on his/her last visit to the site without having to search for them?  An example of a memorable on-line system is Internet Banking. The interface is designed to be self-explanatory and self-evident and, like the ticket machines mentioned earlier, once you have established where to click, you know exactly where to go on your next visit, almost in an “auto-pilot” fashion.
4. Errors – This refers to the amount of errors made by a user during a single visit to a Web site in addition to the severity of the error in terms of cost and time.  If user errors occur, it implies that the systems has made it too easy of the user to make these errors. Either the system is too complex or it is misleading. A user may spend a long amount of time searching for information that is not located where they expect, and thus make errors by clicking on inappropriate links.
5. Subjective Satisfaction – How much do users like using a site’s interface?  On a scale from 1 to 7, where would they rate the interface?  This does not just refer to a site’s homepage but to the entire site, although the homepage is the most important.

The three main goals of usability are:

• To set direction for design, based on user needs, not designer’s whims;
• Ideas based on insights from user needs - their views and ideas of what could be done to improve a site.  These insights are considered to be long-term ideas which are powerful aspects of usability.  They strengthen what works and negate what doesn’t.  They often bring to light unexpected ideas and insights.
• To clean up design and fix usability problems.  This is where the majority of resources are focused. However, this isn’t recommended for the long term.