This is an issue you will want to read. It includes three peer-reviewed articles. It opens with a peer-reviewed essay by Randolph Bias, Clayton Lewis, and Douglas Gillan titled, “The Tortoise and the (Soft)ware: Moore’s Law, Amdahl’s Law, and Performance Trends for Human-Machine Systems.” In it, they compare the rapid growth in information technology documented by Moore’s and Amdahl’s laws to the relatively unchanged basic capabilities of humans, documented by 100 years of behavioral science research. Further, they argue, future increases in the performance of products and systems that combine humans with technology will be limited by the capabilities of the human component. In their stimulating and controversial paper, they urge a renewed focus on usability and human-computer interaction.
JUS has most often included papers on qualitative methods in user experience. The article by Bernard Rummel is a noted exception. Titled, “Probability Plotting: A Tool for Analyzing Task Completion Times,” his paper describes a technique for using the distribution of task time data to diagnose the causes of usability problems. Task time data has been underutilized as a measure of usability because without at least a baseline to compare against, task times from usability tests are difficult to interpret except at their extremes and because summative testing requires a functional system. Most of what we evaluate these days is much earlier in the product development life cycle. The probability plotting technique provides a way to interpret the distribution of times. In addition, Bernard has provided an Excel workbook that automatically computes distributions from task times.
The third peer-reviewed paper is by Joseph Sharit and colleagues. Titled, “The Roles of Health Literacy, Numeracy, and Graph Literacy on the Usability of the VA’s Personal Health Record by Veterans,” the paper shows the value of segmenting the participants in a usability test based on the skills needed to understand and use the information in a website. The authors reviewed a veterans’ Public Health Records (PHRs) website and determined that users might need special skills to take advantage of the value of the site and that older users might have more difficulty than younger ones. They pre-tested a sample of 40 veterans on their abilities in computer, health, and graph literacy and numeracy ability and segmented them into younger and older groups. The 40 participants were then asked to perform 13 health management tasks using the website. The results showed that the better performers scored higher on the pre-test measures and were younger. Graph literacy was the skill that correlated most highly with performance. The value of this study for UX practitioners is in showing the importance of measuring participants’ abilities before a usability test to understand better why some participants are more successful at performing tasks than others.
