Poor search facilities, lack of consistent navigation and bulky PDF files are the major causes of reduced usability, according to Nielsen Norman Group's princi-pal and co-founder Jakob Nielsen.

We studied 14 companies, asking staff to use the corporate intranet for common tasks such as finding information about co-workers or details of a specific employee.

Some intranets worked seven times faster than others.

Businesses should spend at least 10 per cent of their web and intranet budgets on analysing usability, and the other 90 per cent putting the improved service into action, says Nielsen.

'If you spend 90 per cent of your budget doing it, the payback is immense. The return on invest-ment is about 1,000 per cent for the lifespan of the site,' he said.

But the relative immaturity of web design means navigation can be very difficult.

'A lot of companies still use guesswork or rely on market research methods that don’t work for usability, such as showing people screengrabs and asking whether they like them.'

Failing to provide answers to frequent site visitor questions. such as prices, and confusing users with new-look features, are common gripes, says Nielsen.

'There are a lot of mistakes because people are trying to be too clever. Instead they should use their creative forces to make things work well,' he said.

Matthew Berk, senior analyst at analyst Jupiter Research, says user experience is important, but it's also vital to make sure sites add value to the site owner.

Over the next five years, web site investments will be increas-ingly anchored to specific busi-ness goals, and annual spending on site analytics will reach $lbn by 2006, he says.

'The web is eight-years-old commercially, but site design is completely unconnected to how people use them. Great design is often the enemy of usability and a red herring for web sites,' he said.

rachelfielding@vnu.co.uk