Blog Entries
| 6 things you didn’t know about Heuristic Evaluations August 31, 2010 Maybe you already have heard-of and use Heuristics Evaluations. Here are six things you might NOT know about this popular usability method.
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| Should you use 5 or 7 points scales? August 25, 2010 7 point scales tend to perform slightly better than 5 point scales. The benefit is too small to change your existing questionnaires if you have historical data. Having more points will provide the biggest benefit when you have only a few or one question in your questionnaire. Focus more on what you'll do with the results than whether 5 or 7 points is better.
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| 7 Living Legends of Usability August 10, 2010 Love them, hate them, admire them or ignore them. These seven living legends aren't one-hit wonders. Their work has had and will continue to have a large impact on the field of usability for some time.
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| Memory versus Math in Usability Tests August 4, 2010 Confidence intervals, like statistics in general, are powerful because they are both consistent with our experience and provide a level of precision we can't articulate. You should use them with your usability test data.
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| Books Faster than Tablets…or not? July 27, 2010 A study conducted by Nielsen on reading speeds was criticized for going beyond the statistics to support the claim that books are faster than tablets. The crux of this point comes down to considering a finding "statistically significant" only when the p-value is below .05. This criterion is a convention not a commandment and context should always be considered when deciding the role of chance in applied research.
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| A Brief History of the Magic Number 5 in Usability Testing July 21, 2010 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 from 1982-2010.
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| The Five Most Influential Papers in Usability July 7, 2010 These five papers have had a large and lasting influence on the field of Usability and User Experience.
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| Want to Improve Usability? Count Calories June 30, 2010 It is tempting to just find, fix and forget usability problems. It is tempting to skip one milkshake and think you're losing weight. Systematic measuring uncovers patterns and helps prevent major problems.
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| Five ways to make any usability test more credible June 23, 2010 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.
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| Is Usability a Science? June 10, 2010 Usability is not adhering to guidelines. Usability is measuring whether users are actually having a more usable experience. Users might want emotion-evoking software, but if they do there should be some evidence for it.
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| The Faces in the Crowdsourcing May 26, 2010 Mechanical Turk is seeing a shifting of its demographics from stay-at-home moms in the US to younger males in India. Around 60% of the Mechanical Turk workforce will put forth a conscientious effort in completing HITs while around 12% are likely rushing through tasks indiscriminately.
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| Do you need a random sample for your usability test? May 12, 2010 You don't need a random sample to use statistics to make better decisions from your usability data. You do need to know if the users who aren't in your usability tests are different enough than those who are.
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| Will five users really find 85% of all usability problems? May 6, 2010 The sample size formula for finding usability problems only works for a specific set of users and closed-ended tasks. With five users you will only find the more obvious problems.
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| What to do with task times when users fail a task April 29, 2010 For most cases exclude the users who fail the task and call it the average task completion time. Keep the failed task times to report Mean Time to Failure and Average Time on Task.
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| Usability testing is not QA testing April 7, 2010 QA testers are not adequate substitutes for real users and usability tests are not adequate substitutes for good QA.
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| Can you measure task time if users think aloud during a usability test? April 1, 2010 Retrospective probing of user actions and intentions allows you to get a reliable benchmark and identify problems with an interface.
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| Do severe problems affect more users than trivial ones? March 25, 2010 While testing with five users might reveal 85% of problems that impact 31% of users (given a set of tasks and user-type), it doesn't mean you're finding 85% of the critical problems. Assume that the severity of a problem is not related to how often it occurs.
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| How should you display links to PDF files? March 18, 2010 One consequence of analyzing user data is having to reconcile conflicting data-points. How would you display links to PDF files on a web-page?
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| If you could only ask one question, use this one. March 2, 2010 A single 7-point likert-type question asked after a task-scenario provides a quick but sensitive and reliable estimate of task level difficulty and ease.
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| Performance Satisfaction and Perception Satisfaction February 24, 2010 Post-task ratings capture satisfaction with task-performance and are great for identifying problem areas in an interface. Conversely, post-test questionnaires provide overall attitudes about the application and don't provide much diagnostic information.
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| Are the Terms Formative and Summative Helpful or Harmful? February 16, 2010 At some point usability practitioners began using the terms quantitative and Summative interchangeably. That's a bad thing as metrics and quantitative methods should be used when finding and fixing UI problems as well as establishing a usability benchmark.
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| If 1 of 5 users has a problem in a usability test will it impact 1% or 20% of all users? February 1, 2010 Insurance companies do it, drug companies do it and so should usability testers. When you observe a problem from a small sample test, it is unlikely the problem only affects a tiny percentage of users.
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| Do performance data and satisfaction data measure the same thing? January 25, 2010 Performance data such as task times and completion rates explain around 26% of the user's perception of the ease of use. Gather both performance data and satisfaction data to triangulate around the task-level user experience.
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| Can you use the SUS for websites? January 18, 2010 The System Usability Scale (SUS) is the most popular standardized usability questionnaire because it's free and short. It was designed over 20 years ago before the web existed. Should it be used on websites?
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| Does usability exist? January 4, 2010 Is there such thing as usability? This might sound like a silly question considering the industry around usability testing and user experience consulting (not to mention this website). But you can't touch usability and there is no usability thermometer to measure its presence or absence. While we can talk about usability and know it when we see it (or really, know it when we don't see it), what data is there that shows usability exists?
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| What is Quantitative Usability? December 17, 2009 Imagine a marketing department asking for more money to conduct a direct-mail campaign and their only justification was that marketing is a critical business advantage.
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