On Heuristic Evaluation


In the search for insights into usability, heuristic evaluation is the method by which history and experience are applied to the current task. Studies suggest that heuristic evaluations by 3 to 4 usability experts will together identify a substantial proportion of the usability problems with a given interface or application. It is also an excellent low-budget approach for improving usability. The method involves using the interface to accomplish real-world tasks, and noticing the agreement or lack thereof of the interface's design with a checklist of principles of good design - the heuristics.

In this instance, one evaluator will have to do. I am using Nielsen's checklist of general principles. Additionally, the interfaces can be examined for supporting typical search task flows identified from the Query Log Study and critiqued based on principles developed from the MaNIS Interface Design project.

Nielsen's Principles

H1: Visibility of system status

The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.

H2: 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.

H3: 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.

H4: Consistency and standards

Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.

H5: Error prevention

Even better than good error messages is a careful design which prevents a problem from occurring in the first place.

H6: Recognition rather than recall

Make 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.

H7: 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.

H8: 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.

H9: 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.

H10: 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.

Severity Ratings

Each violation of the heuristics above should be given a severity rating, based on the following scale:

0 - Don't think this is a usability problem

1 - Cosmetic problem

2 - Minor usability problem

3 - Major usability problem

4 - Usability catastrophe

Note that a rating of 4 - Usability catastrophe is earned when an application mishandles personal data or personal productivity, or crashes the user's computer. None of these horrible situations are possible with the web-based applications reviewed in this project.

Additional Reviews

Ideally, websites should also be reviewed with W3C's Web Content Accessibility Guidelines 1.0 in mind. (An article at Builder.com provides some perspective on the Guidelines).