Editor’s note: Since writing this column, Steven has done additional user research and has updated his design guidelines for mobile phones accordingly. Read his latest column on this topic: “Design for Fingers, Touch, and People, Part 1.”
As UX professionals, we all pay a lot of attention to users’ needs. When designing for mobile devices, we’re aware that there are some additional things that we must consider—such as how the context in which users employ their devices changes their interactions or usage patterns.  However, some time ago, I noticed a gap in our understanding: How do people actually carry and hold their mobile devices? These devices are not like computers that sit on people’s tables or desks. Instead, people can use mobile devices when they’re standing, walking, riding a bus, or doing just about anything. Users have to hold a device in a way that lets them view its screen, while providing input.
In the past year or so, there have been many discussions about how users hold their mobile devices—most notably Josh Clark’s.  But I suspect that some of what we’ve been reading may not be on track. First, we see a lot of assumptions—for example, that all people hold mobile devices with one hand because they’re the right size for that—well, at least the iPhone is.  Many of these discussions have assumed that people are all the same and do not adapt to different situations, which is not my experience in any area involving real people—much less with the unexpected ways in which people use mobile devices. Read More
What is a confidence interval? I wanted to know that recently and turned to one of my favorite books: Measuring the User Experience, by Tom Tullis and Bill Albert. And here’s what they say:
“Confidence intervals are extremely valuable for any usability professional. A confidence interval is a range that estimates the true population value for a statistic.”
Then they go on to explain how you calculate a confidence interval in Excel. Which is fine, but I have to admit that I wasn’t entirely sure that once I’d calculated it, I really knew what I’d done or what it meant. So I trawled through various statistics books to gain a better understanding of confidence intervals, and this column is the result. Read More
Metrics are the signals that show whether your UX strategy is working. Using metrics is key to tracking changes over time, benchmarking against iterations of your own site or application or those of competitors, and setting targets.
Although most organizations are tracking metrics like conversion rate or engagement time, often they do not tie these metrics back to design decisions. The reason? Their metrics are too high level. A change in your conversion rate could relate to a design change, a promotion, or something that a competitor has done. Time on site could mean anything. Read More