Heuristic Evaluation – Finding Usability Problems
In today’s fast moving design/development environments and straining economy demands that teams become more resourceful in how they practice quality control in interface design.
Not every project has the budget to perform interface design testing. That is a given. However, there are options. Nielsen and Molich developed one such option called Heuristic Evaluation. It is considered and intended as a “discount usability engineering method”.
“Heuristic evaluation (Nielsen and Molich, 1990; Nielsen 1994) is a usability engineering method for finding the usability problems in a user interface design so that they can be attended to as part of an iterative design process. Heuristic evaluation involves having a small set of evaluators examine the interface and judge its compliance with recognized usability principles (the “heuristics”). “
As to the number of evaluators that should be used, Nielsen recommends around 3-5 , as he believes that not much additional information is garnered by increasing numbers. One cannot perform this style of evaluation with a single evaluator because it is nearly impossible for one point of view to find all issues in an interface. Nielsen states, “Averaged over six of my projects, single evaluators found only 35 percent of the usability problems in the interfaces.”
Determining the number of evaluators depends on cost-benefit analysis. In situations where large payoffs of the system would be expected would of course require more evaluators. 1
Reference: Figure 2 – http://www.useit.com/papers/heuristic/heuristic_evaluation.html
A typical heuristic evaluation session usually last one or two hours. The evaluator experiences the interface several times and compares them against the “list of recognized usability principals (the heuristics). They are stated as:
“Visibility of system status
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
Match between system and the real world
The system should speak the users’ language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
User control and freedom
Users often choose system functions by mistake and will need a clearly marked “emergency exit” to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
Consistency and standards
Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
Error prevention
Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
Recognition rather than recall
Minimize the user’s memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
Flexibility and efficiency of use
Accelerators — unseen by the novice user — may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
Aesthetic and minimalist design
Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
Help users recognize, diagnose, and recover from errors
Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
Help and documentation
Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user’s task, list concrete steps to be carried out, and not be too large.” 3
These are used as more or less, general rules for the evaluation. Different sets or heuristics or principals may be used depending on the project. And one approach that has been successfully used with this evaluation is the introduction of usage scenarios into the process.
Results
In the end, the result of the evaluation provides a list of problems encountered with the interface as well as principals that were violated. It does not provide a “systematic” approach to solving all the problems but it does explain issues that were encountered so that the designer is better able to revise their design.
Reference:
1. “Heuristic Evaluation: How-To.” Useit.com: Jakob Nielsen on Usability and Web Design. 17 May 2009 <http://www.useit.com/papers/heuristic/heuristic_evaluation.html>.
2. “Heuristics for User Interface Design.” Useit.com: Jakob Nielsen on Usability and Web Design. 17 May 2009 <http://www.useit.com/papers/heuristic/heuristic_list.html>.
