Heuristic Evaluation - a Step By Step Guide

Evaluation and testing is an important part of your Website development process. Usability tests gather data about the usability of your site by a group of users performing specific tasks.

What is Heuristic Evaluation?

Heuristic Evaluation (originally proposed by Nielsen and Molich, 1990) is a discount method for quick, cheap, and easy evaluation of the user interface.

The process requires that a small set of testers (or "evaluators") examine the interface, and judge its compliance with recognised usability principles (the "heuristics"). The goal is the identification of any usability issues so that they can be addressed as part of an iterative design process.

Heuristic Evaluation is popular in Web development circles because it requires few resources in terms of money, time or expertise. So any developer can enjoy the benefits of usability testing - not just those with thousands to spend on a professional assessment. Heuristic Evaluation is characterised by:

• Small test scenarios that use paper mock-ups or screen shots, which can easily be changed from one test situation to the next
• An informal basis for assessment that doesn't require psychologists
• A high success rate - so only a handful of testers are needed
• A few key guidelines

How can I Use Heuristic Evaluation on my Site?

1. Plan Your Evaluation

How will you test your interface? Heuristic Evaluation typically employs one of the three main approaches:

1. Develop a set of tasks and ask your evaluators to carry them out.

Identify and test the tasks that are critical to your site's success - you'll want all visitors to be able to perform these - and any elements expected to cause difficulty for your site visitors.

2. Provide evaluators with the goals of the system, and allow them to develop their own tasks.

An example goal might be "users should be able to find out how much product x costs." Evaluators can then break this goal down into appropriate tasks, and test each in turn.

3. Ask evaluators to assess your dialogue elements.

Ask evaluators to go through the interface a number of times and examine and assess the efficacy of those elements of your Website that contribute to a dialogue with your site visitors.

Choosing which method to use will depend on you, the time that you have available, and on your evaluators. For example, if you were evaluating with young children, the most appropriate method would be to develop a set of tasks and ask them to carry them out. Children will find this much more achievable than trying to develop their own tasks, or assessing your Website elements without any obvious aims.

2. Choose your Evaluators

The more evaluators you use, the more usability problems you'll reveal. However, studies on the subject have shown that the benefit/cost ratio decreases at about five evaluators. So who should these evaluators be?

• Those with experience - if you can find 5 evaluators who are experts in software ergonomics, and in the field in which the software is applied, a well-planned evaluation program will typically find 81%-90% of usability problems with your interface
• Those without experience - if you don't have 5 free experts at your fingertips, don't worry. A student with no knowledge of software ergonomics will find 22% to 29% of usability problems.

Heuristic Evaluation is known to find more than 90% of usability problems if it's performed by 3 to 5 experienced people... but remember, one evaluator is better than none!