Heuristic Evaluations
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What is a Heuristic Evaluation
In a heuristic evaluation, usability experts review your site’s interface and compare it against accepted heuristics (usability principles). The analysis results in a list of potential usability issues.
A heuristic evaluation should not replace usability testing. Although the heuristics relate to criteria that affect your site’s usability, the issues identified in a heuristic evaluation are different than those found in a usability test.
Advantages
- It can provide some quick and relatively inexpensive feedback to designers.
- You can obtain feedback early in the design process.
- Assigning the correct heuristic can help suggest the best corrective measures to designers.
- You can use it together with other usability testing methodologies.
- You can conduct usability testing to further examine potential issues.
Disadvantages
- It requires knowledge and experience to apply the heuristics effectively.
- Trained usability experts are sometimes hard to find and can be expensive.
- You should use multiple experts and aggregate their results.
- The evaluation may identify more minor issues and fewer major issues.
Nielsen’s Heuristics
Though many groups have developed heuristics, one of the best-known sources is Nielsen’s.
In 1990, Rolf Molich and Jakob Nielsen developed a set of heuristics that are likely the most used in the field of interface design. In 1994, Nielsen refined the list after evaluating several sets of heuristics. Nielsen’s Heuristics include:
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.
References:
- Molich, R. and Nielsen, J., Improving a human- computer dialogue, Communications of the ACM, 33(3), 338-348, (1990).
- Nielsen, J., Enhancing the explanatory power of usability heuristics, CHI'94 Conference Proceedings, (1994).
Expert Reviews
In an expert review, the reviewers already know and understand the heuristics. Because of this, reviewers do not use a specific set of heuristics. As a result, the expert review tends to be less formal, and they are not required to assign a specific heuristic to each potential problem.
