Complementary to user research, or when user research is too costly, a heuristic evaluation can be used to detect and repair usability errors.
Usability experts are given detailed instructions or tasks, a set of usability guidelines, and a reporting format. The experts analyse a product for violations of the guidelines and suggest improvements to the product.
Many product quality reviews are a lightweight form of heuristic evaluation. Working with explicit heuristics and standardized reporting forms however, can greatly improve this practice.