Sep 14 - Mobile Usabiity - Jakob Nielsen's Alertbox

Mobile Usability

The Mobile User Experience Is Miserable

In our mobile studies, the average success rate was 59%, which is admittedly higher than success rates in the 1990s, but substantially lower than the roughly 80% success rate when testing websites on a regular PC today.

Main Mobile Problems

Mobile users face four main usability hurdles:

Small screens. For something to be mobile, it must be easy to carry and thus relatively small. Small screens mean fewer visible options at any given time, requiring users to rely on their short-term memory to build an understanding of an online information space. This makes almost all interactions harder. It's also difficult to find room for multiple windows or other interface solutions that support advanced behaviors, such as comparative product research.

Awkward input, especially for typing. It's hard to operate GUI widgets without a mouse: menus, buttons, hypertext links, and scrolling all take longer time and are more error-prone, whether they're touch-activated or manipulated with a teensy trackball. Text entry is particularly slow and littered with typos, even on devices with dedicated mini-keyboards.

Download delays. Getting the next screen takes forever — often longer than it would on dial-up, even with a supposedly faster 3G service.

Mis-designed sites. Because websites are typically optimized for desktop usability, they don't follow the guidelines necessary for usable mobile access.

Mobile Sites Beat Full Sites

When our test participants used sites that were designed specifically for mobile devices, their success rate averaged 64%, which is substantially higher than the 53% recorded for using "full" sites — that is, the same sites that desktop users see.
Improving user performance by 1/5 is reason enough to create mobileoptimized sites. Such sites were also more pleasant to use and thus received higher subjective satisfaction ratings. This fact offers an additional rationale:
When users are successful and satisfied, they're likely to come back. So, if mobile use is important to your Internet strategy, it's smart to build a dedicated mobile site.
Still, users often had trouble getting to mobile sites, even when companies offered them. The best approach is to auto-sense users' devices and autoforward mobile users to the mobile site (even if they're using a high-end phone). You should also offer clear links from the desktop site to the mobile site, as well as a link back to the full site. As for link labels, we recommend
"Mobile Site" and "Full Site," respectively.

Better Phones Perform Better

There are 3 distinct classes of mobile user experience, and they're mainly
defined by screen size:
Feature phones (regular cellphones) with a tiny screen and a numeric
keypad. These devices account for the vast majority of the market (at
least 85% in some statistics).
Smartphones, in a range of form factors, typically with a mid-sized
screen and a full A-Z keypad.
Touch-screen phones (such as the iPhone) with a nearly device-sized
screen and a true GUI driven by direct manipulation and touch gestures.

Unsurprisingly, the bigger the screen, the better the user experience when
accessing websites. Average success rates were:
Feature phones >> 38%
Smartphones >> 55%
Touch phones >> 75%

For services highly suited for mobile use — such as news or social networking — you should probably create a dedicated feature-phone site, as well as a site optimized for higher-end phones.
Most other websites might be better off concentrating their investment on a single mobile site optimized for smartphones and touch phones.

Mobile Usability Is Hard

All of our new research findings support a single conclusion: designing for mobile is hard. Technical accessibility is very far from providing an acceptable user experience. It's not enough that your site will display on a phone.

Even touch phones that offer "full-featured" browsers don't offer PC-level usability in terms of users' ability to actually get things done on a website.

When designing for mobile, there's a tension between (a) making content and navigation salient so that people do not work too hard to get there, and (b) designing for a small screen and for slow downloading speeds.

Unless websites are redesigned for the special circumstances of mobile use, the mobile Web will remain a mirage.

Source:
Mobile Usability (Jakob Nielsen's Alertbox)
Copyright © 2009 by Jakob Nielsen. ISSN 1548-5552
http://www.useit.com/alertbox/mobile-usability.html