|Applicable stages: design, code, test, and deployment.|
Personnel needed for the evaluation:
|Can be conducted remotely: Yes||Can obtain quantitative data: No|
A heuristic is a guideline or general principle or rule of thumb that can guide a design decision or be used to critique a decision that has already been made. Heuristic evaluation, developed by Jakob Nielsen and Rolf Molich, is a method for structuring the critique of a system using a set of relatively simple and general heuristics.Procedure
The general idea behind heuristic evaluation is that several evaluators independently evaluate a system to come up with potential usability problems. It is important that there be several of these evaluators and that the evaluations be done independently. Nielsen's experience indicates that around 5 evaluators usually results in about 75% of the overall usability problems being discovered.
What is evaluated? Heuristic evaluation is best used as a design time evaluation technique, because it is easier to fix a lot of the usability problems that arise. But all that is really required to do the evaluation is some sort of artifact that describes the system, and that can range from a set of storyboards giving a quick overview of the system all the way to a fully functioning system that is in use in the field.
Let a small set of (usually 4 to 6) human factors engineers examine the interface to be evaluator. Have each individual evaluator inspect the interface alone. Only after all evaluators have completed their individual inspections are the evaluators allowed to communicate and have their findings aggregated.
To aid the evaluators in discovering usability problems, a list of heuristics is provided to them which can be used to generate ideas while evaluating the system. Here is a sample list of heuristics:
- 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 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 men 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.
- Recognition rather than recall
Make objects, actions and options visible. The user should not have to remember information from on 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 to such an extent 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 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.
It should be noted that the heuristics are meant to help the evaluators to find usability problem, but not to restrict them to find only the problem justifiable by the heuristics.