usability testing tips

Usability testing measures the usability, or ease of use, of the product's capacity to meet its intended purpose.

Usability testing tries to measure the value the user was able to derive from a single visit. Did the user find what they were looking for, and are they likely to return or tell someone else?

Usability studies have shown that a website may be aesthetically pleasing, but fail to deliver on it's intended purpose.

 

Key metrics

These are some of the variables which come to play in a usability study:

• Performance. How long and how many steps are required for user to complete a basic task? (eg find a product, create a new account, and order the item.)
• Accuracy. How many mistakes did people make? (And were they fatal or recoverable with the right information?)
• Recall. How much does the person remember afterwards or after periods of non-use? Sites which have poor logic are difficult to learn. They force visitors to relearn the site each time they revisit.
• Emotional response. How does the person feel about the tasks completed? Is the person confident or stressed? Would the user recommend this system to a friend?

  

Continuous usability testing

It is better to receive criticism early, and adjust the course of the project in real time. The later usability testing occurs, the more expensive it becomes to fix.

By the time it is left to the end, fundamental flaws cannot be ironed out because of time and budget constraints.

Make user testing part of the process of development. This approach allows usability to move from being a one-time, report-oriented process to an iterative, action-oriented one. It's much easier to change a whiteboard drawing than a wireframe; easier to change a wireframe than a prototype; and easier to change a prototype than a finished product.

 

When to conduct a usability test

Usability testing is most useful when initiating a new project, to ensure the investment in the project provides the value it was intended to.

Pay particular attention to the user's experience of sites which challenge conventional navigation. New types of functions may appear to be ground-breaking, but may be introduced at the expense of fundamentals such as reading gravity or white space.

Although there may be a strong conceptual reason to challenge convention wisdom, if the experience is foreign, the user is being forced to relearn basics.

For example, taking a standard road map and changing all its icons and colours, will violate common meaning, and disorientate the user.

 

When to avoid usability studies

When someone buys a car, they know it has a shelf life of approximately five years. After five years, the car begins to slow and rust.

Part of this is because the car is becoming fatigued, and part of it is because engineers can make a better car than they did five years ago. You don't need a usability expert to tell you that the car needs to be replaced.

Be careful of usability study that are designed to have an academic outcome. Let the car manufacturers tell us how to best engineer a car, and focus instead on buying the vehicle that best suits your requirements.

 

How usability testing should be performed

Having a usability expert on the team can make a difference. However, there is no substitute for real users.
One way to test a user experience before commencing HTML, is to create a wireframe in Microsoft PowerPoint. A designer is capable of adding buttons, and it is a good simulation of the final experience.

Another route is creating paper prototypes. This is slightly simpler, and involves the subject sitting a facing a light box. Over a light box, an assistant overlays hand-drawn graphics.

Subjects click different parts of the paper screen with a pen, and the assistant replaces the slides with new ones to simulate the website.

 

Measure performance above preference

Performance is measured by how quickly the users were able to complete a scenario. Preference is their like / dislike of the site, based on an overall impression.

Studies have shown that even though users gave sites a low performance score, they still gave a high preference rating.

Preferences are highly subjective, and could be a mixed by influences like design, colour or content. Performance however is much more objective.

Rate performance above preference. Beauty is the eye of the beholder - keep it that way.

Written 1st Nov 2009