Jeff gives lots of examples like "Microsoft noted that by fixing the top 20% of the most reported bugs, 80% of the errors and crashes would be eliminated" and talks a bit about Gerry McGovern's survey method.
I've used Gerry's method lots over the years:
- Highlighting that finding contact details is by far and away the most popular task for university staff using our website; twice as popular as the second ranked task
- Helping support units better understand what is most important to the staff and students they work for
- Prioritising CMS development activities according to what is most important to the user group
But it's not just Gerry that has been preaching this principle.
Lou Rosenfeld in his book Site Search Analytics identifies that search terms used on a site follow the long neck/long tail pattern. So optimising the results your search engine delivers for the top terms used results in a disproportionate improvement in the user experience.
And David Travis has long advocated looking after the 'red routes' through your website at the expense of everything else. Those user journeys that absolutely have to be quick, obvious and trouble-free.
Applying The Pareto Principle To The User Experience - blog post by Jeff Sauro
Red route usability: The key user journeys with your web site - article by David Travis for userfocus.co.uk
Lou Rosenfeld's Search Analytics for your Site - free chapter (my blog post June 2011)
Gerry McGovern white paper on his survey method (my blog post April 2010)