Topics
Topics
Can You Use The SUS For Websites?
The System Usability Scale (SUS) is the most popular standardized usability questionnaire. SUS was developed about 20 years ago at Digital Equipment Corporation by John Brooke. It’s popular for two reasons: it’s free and short (at only 10 questions). The process of taking a set of ordinary questions and making it into a psychometrically valid
Does Better Usability Increase Customer Loyalty?
Would you recommend your cell-phone to a friend? How about the rental car company you just used? Customer loyalty is an important attribute of a product or service’s long-term viability. There are many ways to measure the construct of customer satisfaction and loyalty and they usually involve questionnaires, such as the American Customer Satisfaction Index
Does Usability Exist?
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
What is Quantitative Usability?
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. Now contrast that with an argument that showed that in a previous direct-mail campaign the response rate of 3% was more than twice the industry average and was achieved from
Is There A Difference In Usability Data From Remote Unmoderated Tests & Lab-based Tests?
Why isn’t usability testing done more? And when it is done why is the sample size small? One major reason is the cost. It takes a lot of money and time to bring users into a lab and conduct a usability test. Even if users don’t get compensated for their time, it still takes a
How much is a PhD Worth?
Does a PhD pay off financially? I recently helped conduct the statistical analysis of the UPA 2009 salary survey[pdf], and used this opportunity to look into the data to see if I could calculate how much a PhD affects salaries in this profession. The dataset contains salary information for a wide range of jobs in
Do Users Fail A Task And Still Rate It As Easy?
Have you ever watched a user perform horribly during a usability test only to watch in amazement as they rate a task as very easy to use? I have, and as long as I’ve been conducting usability tests, I’ve heard of this contradictory behavior from other researchers. Such occurrences have led many to discount the
Margins of Error in Usability Tests
How many users will complete the task and how long will it take them? If you need to benchmark an interface, then a summative usability test is one way to answer these questions. Summative tests are the gold-standard for usability measurement. But just how precise are the metrics? Just as a presidential poll uses a
Deriving a Problem Discovery Sample Size
Nielsen derives his “five users is enough” formula from a paper he and Tom Landauer published in 1993. Before Nielsen and Landauer James Lewis of IBM proposed a very similar problem detection formula in 1982 based on the binomial probability formula.[4] Lewis stated that: The binomial probability theorem can be used to determine the probability
Task Times in Formative Usability Tests
It is common to think of time-on-task data gathered only during summative evaluations because, during a formative evaluation, the focus is on finding and fixing problems, or at least finding the problems and delivering a report. For a variety of reasons, time-on-task measures often get left out of the mix. In this article, I show
SUM: Single Usability Metric
SUM is a standardized, summated and single usability metric. It was developed to represent the majority of variation in four common usability metrics used in summative usability tests: task completion rates, task time, satisfaction and error counts. The theoretical foundations of SUM are based on a paper presented at CHI 2005 entitled “A Method to
Restoring Confidence in Usability Results
Adding confidence intervals to completion rates in usability tests will temper both excessive skepticism and overstated usability findings. Confidence intervals make testing more efficient by quickly revealing unusable tasks with very small samples. Examples are detailed and downloadable calculators are available. Are you Lacking Confidence? You just finished a usability test. You had