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We’ve written extensively about how to determine the right sample size for UX studies. There isn’t one sample size that will work for all studies. The optimal sample size is based on the type of study, which can be classified into three groups: Comparison studies: Comparing metrics for statistical differences Standalone studies: Estimates a population metric (such as completion rate or perceived ease) Problem discovery:

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In an earlier article, we examined the relationship between NPS and future company growth. We found the Net Promoter Score had a modest correlation with future growth (r = .35) in the 14 industries we examined. In the 11 industries that had a positive correlation, the average correlation with two-year revenue growth was higher at r = .44. This ranged from a high of r

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The NASA TLX is a multi-item questionnaire developed in 1980 by Sandra Hart. NASA is, of course, the US-based space agency famous for the one giant leap for mankind. The TLX stands for Task Load Index and is a measure of perceived workload. If you conduct mostly digital UX research for consumers (websites and software), you may not have used the NASA TLX, but as interfaces

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In an earlier article, we examined the folk wisdom that three-point scales were superior to those with more, such as five, seven, ten, or eleven response options. Across twelve published studies we found little to suggest that three-point scales were better than scales with more points and, in fact, found evidence to show that they performed much worse than scales with more points. Almost all

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Five-point scales are the best. No, seven points. Never use a ten-point scale. Eleven points “pretend noise is science.” You never need more than three points. Few things seem to elicit more opinions (and misinformation) in measurement than the “right” number of scale points to use in a rating scale response option. For example, here is a discussion on Twitter by Erika Hall making the

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In user research, there’s more than one expert and there’s also more than one expert review. The 1990s were the golden age of what is loosely referred to as expert reviews or by the more general term inspection methods. Unlike usability testing, which relies on observing users interact with a product or website, inspection methods—as the name suggests—are based on evaluators examining an interface for

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What gets measured gets managed. It’s more than a truism for business executives. It’s also essential for the user experience professional. In business, and UX research in particular, you don’t want to bring focus to the wrong or flawed measure. It can lead to wrong decisions and a misalignment of effort. In an earlier article, I discussed the differences between the most common variables in

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UX professionals use many methods to help understand and improve the user experience. Among the most popular are usability testing, expert reviews, surveys, and card sorting. But where did these methods come from? The field of UX research is relatively new, but its methods are not. And while UX methods may have new names, many of these methods are specialized adaptations of methods with roots

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UX research pulls many terms, methods, and conventions from other fields. Selecting a method is an important first choice in measuring the user experience. But an important next step is understanding the variables you’ll have to deal with when designing a study or drawing conclusions. Variables are things that change. Variables can be controlled and measured. It sounds simple enough but there are actually different types

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Methods evolve and adapt. The same is true of UX methods that have evolved from other methods, often from disparate fields and dating back decades. The usability profession itself can trace its roots to the industrial revolution. The think aloud protocol, one of the signature methods of usability testing, can trace its roots to psychoanalysis, with influence from Freud, Wundt, and Skinner dating back over

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