Fall 1994
Gregory Abowd
This explanation of Heuristic Evaluation is adapted from the following sources:
Clayton Lewis and John Rieman, Task-Centered User Interface Design: A practical introduction.. A shareware book published by the authors, 1993. Original files for the book are available by FTP from ftp.cs.colorado.edu.
Jakob Nielsen, Heuristic Evaluation. In Jakob Nielsen and Robert L. Mack, editors, Usability Inspection Methods. John Wiley and Sons, Inc. 1994.
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.
The general idea behind heuristic evaluation is that several evaluators independently critique 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.
To aid the evaluators in discovering usability problems, there is a list of 9 heuristics which can be used to generate ideas while critiquing the system. Here is the original list of heuristics.
The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
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.
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.
Users should not have to wonder whether different words, situations, or actions men the same thing. Follow platform conventions.
Even better than good error messages is a careful design which prevents a problem from occurring in the first place.
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.
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.
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.
Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
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.