Using the web isn’t easy on mobile devices, especially in the case of websites not designed for mobiles, according to usability studies from Jakob Nielsen.

According to Nielsen, mobile sites performed poorly in user testing, with the average success rate for tasks performed on mobiles just 59%, compared with 80% for regular websites.

The main problems are:

  • Small screens. Obvious really, but small screens mean that there are fewer visible options, making interactions on mobiles much more difficult.
  • Difficulty of data input. As with small screens, small keyboards make it harder to type, to scroll up and down web pages, and increases the possibility that mistakes will be made by users.
  • Slow download times. Variable connection speeds and quality means that loading uo web pages can take a long time. Nielsen compares this slowness to dial-up internet.

  • Sites not designed for mobiles. Since most websites are designed for desktop users, they can be harder to use on a mobile. 

The answer? Design sites especially for mobile users, and hope they are accessing them with touch screen devices.

When users in Nielsen’s tests were accessing sites optimised for mobiles, the average task success rate was 64%, compared to 53% for standard websites. So, if your mobile strategy is important designing a website with mobile user in mind is the key.

There are some good examples of sites that have done this; both Amazon and FT.com have sites that have been optimised for mobiles, providing a usable site by stripping out some of the functionality of the main websites, and, in Amazon’s case, streamlining the product search and checkout process.

The other issue here is to make mobile websites easier to find, something I have mentioned before. Automatically redirecting users to mobile versions of sites and providing clear links from desktop sites to the mobile versions will help users.

There are also clear differences in usability between different types of mobile phones. Touch screens, such as that on the iPhone, offer the best experience, followed by smartphones, while regular phones, which make up the majority, offer the poorest mobile internet experience for users.

The key is to work out the audience for your website before you decide which phones to optimise for. In the case of FT.com, it had a high percentage of users with Blackberries and iPhones, so the site is aimed at these devices, while an excellent iPhone app has also been released.

For other sites, a one-size fits all policy may be best, to provide the best user experience for as wide as audience as possible.