Practical usability rating by experts.
A couple of months ago I was introduced to the usability method PURE (practical usability rating by experts), created by Christian Rohrer and Jeff Sauro. It is an analytical method that does not involve direct contact with users, great for identifying friction in task that cannot be tested with users because of cost, priority, difficulty, etc.
“(…)a method that provides a type of score to estimate the amount of “friction” a typical participant is likely to encounter while using an interface. The method is called PURE, or Practical Usability Rating by Experts, and is based on experts familiar with UX principles and heuristics, who rate a user experience based on a pre-defined rubric.”
A group of 2 or more experts will individually score the amount of friction a user may find during a given task. The process begins by selecting a persona and the tasks in which he will go through.
The experts must then break down the tasks into specific steps, and score them in a 3 point scale. The intriguing aspect of PURE, in my view, is that the group must come to a consensus of the sum of scores, and agree on one rating per step.
The overall color for the task and the product is determined by the worst score of a given step within that task and product. For example, a single red step (rated 3) in a task causes that entire task and product to be colored red. The rationale for this is that no mature consumer product should have a step in which the target user is likely to fail a fundamental task.
I find that the “social” aspect of PURE to be an interesting experience in terms of developing the skill to listen and become aware of your own biases. The discussion of each individual step takes into account who your persona is, their objectives within the task, and potential friction they may encounter. Your perception of what the user will be able to accomplish with ease and what will cause them to fail (a step or the entire task for that matter), is as insightful personally as it is to the team of experts.
Sharing a common score is also vital for stakeholder buy-in, especially if the evaluated task is considered to be controversial. Experts from different teams will help in maintaining the group impartial to the end result.
A 3-point scale may seam odd during the first couple of tasks, but the experts’ tend to get in sync. If needed, be sure to have metrics that can help the group reach an agreement.
PURE does not replace usability testing overall, rather than being one additional option for your user research toolkit.
Thanks to Jeff Sauro and Christian Rohrer for sharing their great work. You can check out their CHI paper here.