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I write a lot about the importance of confidence intervals and making the most of small sample sizes. Recently, Dean Barker, director of UX at Sage CRM read one of the articles on margins of error and sample sizes and said: "I understand there is variability with small samples but I'm having a hard time reconciling the numbers with my experience."   Math Dean was

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Recently Nielsen conducted a study on the reading speeds between the printed book, Kindle and iPad. From 24 users the study concluded that the iPad took about 6.2% longer (p =.06) and Kindle about 10% longer (p <.01) to read than the same story on a printed book. From this data Nielsen concluded "Books Faster than Tablets" and while tablets have improved dramatically over the

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Wondering about the origins of the sample size controversy in the usability profession?  Here is an annotated timeline of the major events and papers which continue to shape this topic. The Pre-Cambrian Era (Up to 1982) It's the dawn of Usability Evaluation and the first indications of diminishing returns in problem discovery are emerging. 1981: Alphonse Chapanis and colleagues suggest that observing about five to

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Will users purchase an upgrade? What features are most desired?  Will they recommend the product to a friend? Part of measuring the user experience involves directly asking users what they think via surveys. The Web has made surveys easy to administer and deliver. It hasn't made the question of how many people you need to survey any easier though. One common question is "How many

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I compiled a list of papers that have had a large and lasting influence on the field of Usability and User Experience. I then asked Jim Lewis and Joe Dumas, two pioneers in this field for their top five.  There was considerable overlap in both the papers and topics suggesting that while there may be some disagreement with the conclusions of the papers there is

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When babies are born in the hospital nurses measure every feeding and diaper change. When you want to lose weight with Weight Watchers you log everything you eat using a point system. When you want to improve usability beyond obvious problems you need to record: symptoms:  lower completion rates, lower satisfaction ratings, longer task times or more errors. causes:  what design elements are leading to

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Whether you're conducting an early stage test of a prototype or late validation, these five tips can make any usability test more credible. The tips both temper skepticism about small samples and help you avoid overstating your findings. Count the number of users that experience each problem. Early testing is all about finding and fixing usability problems. But make those problem lists even more helpful

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With usability testing it used to be that we had to make our best guess as how users actually interacted with software outside a contrived lab-setting. We didn't have all the information we needed. Knowing what users did was in a sense a puzzle with a lot of missing pieces. Web-analytics provides us with a wealth of data about actual usage we just never had

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Is manufacturing a science? Is marketing a science? Is engineering a science? None of these are sciences. But they all can be informed by science or ignore science. To be "scientific" is to rely on observation and measurement instead of intuition and superstition.  Controlled experiments, surveys, observational studies, testing and validation can be used in all stages of these industries to make better decisions. These

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It's been ten years since the dot-com flame-out began. In those ten years we've seen the rise of User Experience. User Experience seems to have a lot of buzz and gets attached to all sorts of activities that have little to do with the user or the experience. It has all but replaced the terms usability and human factors in many companies (it is also

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