Jakob Nielsen‘s
Alertbox, September 26, 2011


Mobile Usability Update


The user experience of mobile websites and apps has improved since our last research, but we still have far to go. A dedicated mobile site is a must, and apps get even higher usability scores.

There’s no need to declare this “the year of mobile.” If anything, last year was the year of mobile in terms of the growth in both mobile usage and the availability of mobile sites and apps. Now, however, it’s time to redesign your mobile site, because your existing version is probably far below users’ growing expectations for user experience quality.

The mainstream Web’s history repeats itself here. In the beginning, the Web was experimental — accordingly, it was acceptable to have a somewhat shaky, experimental website. Many sites were crippled by misguided design advice, which was common in the early years, and most companies didn’t know any better (because they didn’t do usability studies). Now, people simply expect websites to work.

Same with mobile. Last year, it might have been cool simply to have an app. Now, that app better be good. Requirements have gone up. Luckily, our new research shows that mobile sites and apps have been improving their usability, even though it’s still far below that of regular websites accessed from a desktop computer.

User Research

We conducted 8 rounds of user testing: 5 in the United States, and one round each in Australia, Hong Kong, and the U.K.

The first 2 rounds of testing were conducted in 2009 and were discussed in an earlier article. In that initial research, we tested all three categories of mobile phones:

  • Feature phones: primitive handsets with tiny screens and very limited keypads that are suited mainly for dialing phone numbers.
  • Smartphones: phones with midsized screens and full A–Z keypads.
  • Touch phones: devices with touch-sensitive screens that cover almost the entire front of the phone.

For our 6 new studies, we dropped the feature phones for three reasons:

  • Our first research found that feature phone usability is so miserable when accessing the Web that we recommend that most companies don’t bother supporting feature phones.
  • Empirically, websites see very little traffic from feature phones, partly because people rarely go on the Web when their experience is so bad, and partly because the higher classes of phones have seen a dramatic uplift in market share since our earlier research.
  • Pragmatically, almost all participants in our mobile user experience courses tell us that they don’t design for feature phones. Thus, we don’t need to collect updated video clips or other seminar materials about feature phones.

In the first 2 test rounds, touch phones were mainly iPhones, with a smattering of competing, though primitive, devices. In the recent testing, we still had many iPhone users but also many Android users as well as some Windows Phone users.

All together, we tested 105 users — 53 males and 52 females. Of those test participants, 12% were 50 years or older, while the remaining 88% were evenly distributed across the ages of 20–49 years. Occupations ran the gamut, from fashion consultant to patent lawyer to television producer.

Tasks ranged from directed to exploratory:

  • Highly specific tasks. For example, “You are in an electronics store and consider buying a Canon PowerShot SD1100IS as a present. The camera costs $220.25 in the store. Check adorama.com to see if you can get a better price online.”
  • Directed, but less specific. For example, “Find a moisturizer with SPF 30 or above that is suitable for your skin.” (While using the Walgreens app.)
  • Open-ended, but restricted to a predetermined site or app. For example, “See if you can find any interesting pictures related to today’s news.” (While using the China Daily app.)
  • Web-wide tasks that let users go anywhere they wanted. For example, “Find out which is the tallest building in the world.” (While giving users no indication of which site might have the answer.)

In all, we observed participants doing 390 different tasks: 194 application-specific tasks, 154 website-specific tasks, and 42 Web-wide tasks.

In addition to user testing, we also conducted 2 rounds of diary studies to discover how people use mobile devices in their everyday life. One diary study was in the U.S.; the other included participants from Australia, The Netherlands, Romania, Singapore, the U.K., and the U.S. In total, 27 people participated in the diary studies, providing us data about 172 person-days of mobile activities. Again, participants had a wide range of jobs, from bookkeeper to football coach.

Mobile User Experience Improving Slowly

In the 1st edition of our report, mobile users’ average success rate was 59%.

In the new research, the average success rate was 62%. Better, but only 3 percentage points better in 2 years. Although this improvement rate might seem disappointingly slow, it’s about the same as the pace we recorded for desktop Web use in 263 studies over the last 12 years.

The current success rate for mobile Web use is about what we measured for desktop Web use in 1999. The current desktop success rate is 84%; unless mobile usability starts improving more rapidly, we’ll have to wait until 2026 to reach that level.

The 62% success rate was computed across all tasks that we could reasonably categorize as having been done correctly or incorrectly.

Measured usability varied substantially, depending on whether people used a mobile site or a full website. (By way of definition, a “mobile” site is one designed specifically for use on mobile devices, whereas a “full” site is a regular website designed mainly for use on a full-screen desktop computer.)

  • Mobile site success rate: 64%
  • Full site success rate: 58%

This leads to the first, and maybe most important, guideline for improving the mobile user experience: design a separate mobile site. Don’t expect users to access the same site from both desktop and mobile browsers. (The exception would be people using large-sized tablets like the iPad. Our separate studies of iPad users show that they do fairly well browsing full sites.)

A second key guideline is to have clear, explicit links from the full site to the mobile site and from the mobile site to the full site. Unfortunately, search engines often fail their mobile users and erroneously point them to the full sites, even for companies that offer mobile sites with much better user experience. As long as users don’t need to navigate, they might actually be okay when they’re dumped into a site that works poorly on their phone. Search engines frequently offer deep links to pages directly related to the user’s query. But if users want to know more than what that one page offers, they’ll suffer if they’re stuck on the full site. That’s when the link to the mobile site will come in handy. (And why the search engines should have pointed to the mobile site in the first place.)

Apps Beat Sites

While a mobile site is good, a mobile app is even better. We measured a success rate of 76% when people used mobile apps, which is much higher than the 64% recorded for mobile-specific websites.

Of course, it’s more expensive to build an app than a mobile site, because you have to code different versions for each platform. Thus, we can really recommend building mobile applications only if you’re either rich or offer a service that’s particularly suited to mobile use.

Most Usability Guidelines Confirmed

The 1st edition of our mobile usability report contained 85 design guidelines. Of these, 83 were confirmed by the recent research, 1 was somewhat revised, and 1 was deleted. As I’ve said many times before, usability guidelines remain very stable over the years because they mainly depend on human behavior. (The one guideline that was revised related to the use of Flash, and was thus more technology-dependent than most usability guidelines.)

The main news? From the 1st to the 2nd edition of our mobile usability report, the number of design guidelines increased from 85 to 210. This is partly because we now know much more about mobile usability and partly because requirements have increased. Sites and apps have definitely gotten better, raising the bar for acceptable user experience, and thus increasing the number of guidelines that designers should follow.

In particular, Android apps have gotten much better, probably because the platform’s growing market share has caused companies to invest more in the quality of their Android apps.

Also, users have become more aware of horizontal swiping than they were in our previous research. The horizontal swipe gesture is often used to “flip” through deck-of-cards or carousel features. Swiping is still less discoverable than most other ways of manipulating mobile content, so we recommend including a visible cue when people can swipe, or they might never do so and thus miss most of your offerings. Also, you should avoid swipe ambiguity: don’t employ the same swipe gesture to mean different things on different areas of the same screen. This recommendation is the same for mobile phones and tablet usability, showing the similarity between these two gesture-based platforms.

It’s interesting to consider the difference between mouse-driven desktop design and gesture-driven touchscreen design here. Desktop websites have a strong guideline to avoid horizontal scrolling. But for touch-screens, horizontal swipes are often fine. Indeed, mobile-device users typically expect to horizontally swipe their way through a carousel. Of course, this is just one more example of the meta-guideline that sufficiently different platforms require different user interface designs. This, again, is the underlying reason that mobile sites perform better than full sites when used on a mobile device.

Mobile Design = Small and Targeted

To have a successful mobile site or app, the obvious guideline is to design for the small screen. Sadly, some don’t, and we still see users struggle to hit tiny areas that are much smaller than their fingers. The fat-finger syndrome will be with us for years to come.

The second point is more conceptual — and harder for some people to accept: When you have a smaller screen, you must limit the number of features to those that matter the most for the mobile use case.

Learn More

293-page report on Usability of Mobile Websites and Applications with 210 design guidelines and 479 screenshots is available for download.

Full-day training courses at

the annual

Usability Week conference:

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Copyright © 2011 by Jakob Nielsen. ISSN 1548-5552