In the last few years, as users have struggled with web pages and other software, designers have become interested in usability. As specialists in audience research, we find that a growing proportion of our work is in this area; assessing and improving web site usability, in particular. But usability has its limitations, we've discovered. So now we are moving onto the broader concept of effectiveness - developing a method for assessing the effectiveness of websites. It's a 7-stage model, which will eventually supersede this page.
To know whether a site is usable, you first must know what it is setting out to do. Many sites have been set up without a clear reason, or a way of evaluating their success. A lot of companies seem to have decided "all our competitors are getting web sites, so we should have one too." Usually they end up spending far more money than they intended to, because web development is very labour intensive. And then, perhaps, nobody visits.
Every business with a website has become a publisher, but businesses often don't realize this. In fact, many businesses were publishers before they had websites, producing annual reports, brochures, catalogues, advertisements, and so on - but all done by different departments, without coordination.
Many web sites end up serving a wide variety of purposes - so the whole site can't be evaluated with the same criteria...
Some desirable characteristics are shared by all web sites - for example,
The site should be available nearly all the time
It should have a low downtime level, and start loading quickly. A lot of visitors give up if they wait 10 seconds and nothing happens.
The site should be easily accessible to its potential users
This involves having a short and memorable URL (for easy typing), and a simple navigation structure. If the site has more than about 10 pages, it should have a search engine that works well. (Many don't - try the Microsoft site, for example; if you don't search the right part, you won't find what you want. But of course this task is harder for a large site than a small one.)
Users should have at a pleasant experience when visiting the site
If they leave it feeling annoyed, they're unlikely to return.
When users find what they want, it should be up to date and accurate
Again, this is obvious - but you don't have to look very hard to find a web page that's years out of date. As for accuracy, this needs to match the purpose of the site. Obviously it's more important for a site that gives details of dosage for anti-cancer drugs than for a fiction site.
Users should be able to find what they want quickly
This has several aspects: one is fast downloading of pages. We did a small survey, and found that the average home page is about 60K bytes (one byte is roughly equal to one letter). The average modem runs at about 3K bytes per second. Don't be fooled by "56K" descriptions: those are bits, which are much smaller than bytes, and most of the time modems can't run at full speed anyway. Thus the average home page takes about 20 seconds to download for the average user. In developing countries, and places with old telephone systems, it can be many times longer than that.
Evidence from psychological research shows that most people start thinking of something else after about 7 to 10 seconds, and that the ideal delay for effective feedback is about half a second. (Imagine trying to drive if you couldn't see the road for 10 seconds after you turned the wheel.) Combine this information with the download time for a 50K page, and you begin to understand the loss of potential due to large pages. On the other hand, a succession of pages that are very small is also annoying. Our research suggests that an ideal size is about 10K - around 3 printed pages for one web page without photos.
A related problem is having to search numerous pages when you're not exactly sure what you're looking for. So one substitute for a slow line speed is a good site search.
Pages should be readable when printed
A lot of people don't like to read from a computer screen. If a web page is more than a single screen, they prefer to print it, and read it on paper. Many websites make no allowance at all for printing - often they chop off the right-hand side of each page. With the 2003 and later versions of Mozilla and its mutations such as Firefox, this irritating problem is mostly fixed, by selecting "fit to page". But most people still use Internet Explorer, where the problem remains.
Web pages should look much the same on different browsers
Though Internet Explorer is by far the most popular browsers, there are plenty of others - and even IE comes in numerous versions, for numerous operating systems. The annoying thing (for some site owners) is that they all present web pages slightly differently. It's never possible to satisfy all users: you have to decide what percentage of low-end users you will abandon, and what percentage of high-end users you won't make the most of. It depends on your target audience. With Audience Dialogue, for example, because many of our visitors are in developing countries with poor computer facilities, we try to keep the pages small (so that they don't take too long to load) and technically simple (so that people using old browsers and computers can access this site).
Pages with a lot of words should be easy to read on the screen
Many are appalling, with tiny print and flashing advertisements. Because this site is mostly words, we've tried to make it easy for you to read - but it's partly up to you. For example: do you find this font too large or small for comfortable reading? If so, and you're using Internet Explorer version 5 or 6 on a PC- so go to the View menu, then to Text Size, and choose a different font size. Other browser software has similar options.
If a page is about one topic (as most are) it should convey one clear message
Some websites are designed as if space on computer screens is very expensive. These sites look like old-fashioned newspapers, with small print crammed into multiple columns. This may be based on the idea that users don't like to scroll down. Well, of course they don't like scrolling down then up again, to read text in columns. Often a multi-column layout confuses readers, and makes it harder for them to find what they want.
A site should be accessible to everybody
Though "accessibility" is often seen as catering for the disabled, it's much broader than that. Visit an internet cafe in Indonesia (look for a WARNET sign) and you'll find that a page that seems fine on a broadband line at home can be unusable when the modem is ultra-slow and the computers aren't well maintained. How does your site work if a user has a mouse that's hard to control because it's full of fluff? Or if they're using VISCII rather than ASCII? All sorts of things can go wrong, and websites that try to be "cutting edge" are often unreadable by many potential visitors.
A website should invite feedback
What's the use of trying to communicate with people if you don't let them communicate back? Here's a puzzle for you: visit the much-touted Amazon Books site, and just try to find a way to contact Amazon by email. The implicit message: "Don't try to talk to us, we're much too busy to bother with you." (As soon as you order a book, though, Amazon becomes much more communicative.)
Those are the properties that any successful website should have. But depending on what it's trying to do (if it knows that!) other factors will also be important.
For example: a site used for online sales has two clear criteria:
- easy to find what you want to buy
- easy to buy it
- plus assuring new visitors that this business is safe to deal with.
This line of thought is continued on our page about website evaluation.
Here are a few key sites with more information on usability, and related topic, such as readability and legibility. (However, none of these extends into the area that Audience Dialogue is currently focusing on - effectiveness. See our work-in-progress page on effectiveness of websites.)