We already saw how a manageable sample of users can provide meaningful data for discrete-binary data like task completion. With continuous data like task times, the sample size can be even smaller. The continuous calculation is a bit more complicated and involves somewhat of a Catch-22. Most want to determine the sample size ahead of
Continuous Data Efficiency is one of the cardinal aspects of a product’s usability. The amount of time it takes for a user to complete a task is one of the best predictors of efficiency because it: Illustrates the slightest variability (in seconds) that are more difficult to detect in other measures like errors Is a
If you compare the sigma value on this site with other values published in most six sigma literature, it’s important to know that a 1.5 σ “shift” is usually added. For example, if you see a sigma value of 1.08σ on measuringusability.com and want to compare it to other sources then add 1.5. The resulting
