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Quantitative Usability, Statistics & Six Sigma by Jeff Sauro

Blog Entries

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? Read

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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. Read

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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. Read

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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. Read

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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. Read

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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. Read

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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? Read

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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? Read

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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. Read

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