Research: Usability Testing

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

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

UX researchers and other project stakeholders often fervently debate the number of participants that are necessary for usability studies. At the core of this debate is often the tension between the usability professional’s desire for the best possible study and the business team's desire to reduce time and expense.

In 2009, Ritch wrote an article for the Journal of Usability Studies titled “How to Specify the Participant Group Size for Usability Studies: A Practitioner’s Guide” to address this issue. He based his article on a wide survey of the literature then available, and his intent was to help usability professionals make clear recommendations for the size of participant groups in particular contexts, as well as to understand the basis for those recommendations and their associated risks. Read More