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Heuristic evaluation
for the web

-- sidebar to lecture notes on use-oriented web design --
 

Heuristic evaluation is an inspection method based on ten general guidelines for good usability. Three to five usability experts independently evaluate the interface in question. They report any potential usability problems structured along the guidelines. It is desirable if they can also rate the severity of the problems.

The method is developed by Jakob Nielsen. The following is Nielsen's guidelines, with my web-specific comments and a few examples.

1. Visibility of system status. "The system should always keep users informed about what is going on, through appropriate fedback within reasonable time."

The key to web usability is to know where you are and where you can go. The ability to predict where a link leads is crucial. In the example from Passagen, a brief introduction to the participants and the contents of the chat record would help a lot.

2. 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."

The term 'Beställ' (Order) in most contexts, on the web and in the real world, means to place an order. However, the link in this example does not give you a form for ordering the fine product.

Instead, it takes you to a standard page with phone and email contact info. Moreover, that info is already available in the menu on the left.

3. 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."

The main exit on the web is, of course, the Back function. Do not deactivate it. Also be careful with opening new browser windows. Many users do not notice the old window underneath, and end up confused when the history list is empty.

But you can do better than simply leaving Back alone. In this example from Toga.com, you walked the path through Product categories, Sweaters and a particular brand to end up on the page describing one product. If that is not exactly what you are looking for, why not provide clearly marked links to five or ten similar products? That would be a more constructive exit.

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

The platform in question is the more-or-less established web conventions. Navigation device at the top of the page can be repeated or summarized at the bottom; text links are blue and underlined; the words 'site map' refers to a table of contents; and so on.

Consistency between links, page titles and page headings is important to avoid confusion.

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

The most frequent error in web travel is going somewhere you did not intend to. Links must be predictable. (Not that there is anything wrong with serendipitous discovery, but the serendipity should occur pre-click. Nothing kills your interest in a site like waiting for a large page to download before being able to tell that it is not what you expected.)

6. 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."

If you are looking to buy a used car at Bilnytt, it takes you a while to find the Buying Used Cars link and even longer to read the article associated with it. It mentions a joint venture with Bytbil but there is no link! I still don't know if there is a way to buy used cars at Bilnytt. (I finally typed www.bytbil.com into the browser URL field.)

7. 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."

The best accelerator on the web is the bookmarks provided by the browser. An ideal design from the users' perspective would provide distinct, stable URLs to each page (avoiding frames, not too volatile generated HTML, etc.). On the other hand, many developers of frame-based sites have a strong interest in channeling their hits through the first page, where they can present current offers. This is clearly an issue where usability is at odds with common marketing sense. Or is it? What if the current offers appeared in the bookmarkable content page?

8. 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."

This is a strange guidelines compared to the others, in that it advocates one particular style on fairly loose grounds. For purely task-oriented systems, it might hold (even though there is some evidence to the contrary). On the web, it is even harder. More and more sites become mini-portals offering a smorgasbord of stuff for a heterogeneous audience. What is 'irrelevant or rarely needed' in that context?

9. 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."

Providing helpful error messages is hard work. But at the same time, it can be difference between repeat business and going elsewhere. This all-purpose message is what you get at Torget when you try to locate countryside hotels in southern Sweden through the Advanced Search facility. Most users would probably stop looking at this point.

10. 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.

The problem with most web help is the very concept of web pages. You click for help, you are taken to a new page with lots of information, you forget what you were doing when you asked for help. Think about ways of providing more context-sensitive and integrated help when necessary. Some ideas may involve layers, frames, ALT tags, status line, or JavaScript.

Jakob Nielsen, the originator of heuristic evaluation, has written a lot on the method, its use and its validity. See the web material at useit.com.

Keith Instone describes in an article at webreview.com how heuristic evaluation translates to the web. Some of the points here are based on his work.

Jonas Löwgren home page -- teaching material -- use-oriented web design -- heuristic evaluation