The PURE (Practical Usability Rating by Experts) Method is a usability evaluation technique in which experts evaluate a product or interface based on predefined tasks. These tasks are representative of what end-users would typically perform on the interface. Chris Hass and Jared M. Spool developed this method from User Interface Engineering (UIE). 
Components of the PURE Method
The PURE Method involves a few key components:
- Tasks: Experts perform a set of tasks that are representative of the user's goals.
- Path: A user's path to complete the task is mapped out.
- Ratings: Each step on the path is scored for complexity and ease of understanding.
- Evaluation: The scores for each step are combined to produce a score for the task, and the scores for all tasks are combined to produce an overall usability score.
Purpose and Role
The PURE method aims to identify usability issues and opportunities for improvement in an interface. It's used to:
- Evaluate the usability of a design early in the design process, even before a working prototype is available.
- Compare and measure the usability of different designs.
- Track changes in usability over time or across different product versions.
The PURE method provides a quantitative measure of usability, which can be beneficial for comparing different designs or tracking improvements over time. It can be conducted early in the design process, helping teams catch and correct usability issues before they become too costly or time-consuming.
Pros and Cons
- It allows for usability evaluation at an early stage, even without a working prototype.
- It provides a quantitative measure of usability.
- It relies on expert judgment, which may not always align with actual user behavior.
- It can be time-consuming to perform, especially for complex interfaces with many possible paths and tasks.
For example, a team designing a new e-commerce website might use the PURE method to evaluate the site's usability. They would identify key tasks users need to perform on the site (such as searching for a product, adding a product to the cart, and checking out), map out the path users would take to complete each task, and then rate each step on the path for complexity and understanding. The scores from each task would then be combined to provide an overall usability score for the site. This score could be used to identify areas of the site that need improvement and to track changes in usability as the design is refined.
- Defning the PURE Method MeasuringU