A product's usability depends on many attributes. A usable product is easy to install, provides unambiguous choices when users must take action, has clear and relevant supporting documentation, lets users efficiently complete a task without relying on documentation or customer supports calls, and enables opportunistic learning (e.g., through understandable error messages or confirmation messages that warn users of risky commands before the product executes them).

Usability professionals often must balance first-time usability and experienced-user performance, because features that simplify learning for the first-time user can become tedious after you use a product several times. However, undeleting is an infrequent task that requires instant usability. Undelete programs pose special usability challenges, because making a mistake can be fatal. You might accidentally overwrite the files you're trying to restore.

Researchers use a variety of techniques to measure usability, such as formal tests, rapid prototyping tests that evaluate preliminary storyboards and simulations, and expert reviews (e.g., cognitive walkthroughs, heuristic evaluations). To perform usability tests on undelete utilities for Windows NT Magazine, Lodestone Research conducted an expert review.

The company evaluated performance measures (e.g., ability to complete the task, amount of time required), organization of menus and screens, clarity of messages, and whether users could complete tasks without relying on documentation or customer support. The tests focused on three tasks: installation, recovering a lost file, and recovering a lost directory. To see the undelete utility usability report, go to http://www.lodestone.com and click New at Lodestone. Then, click Windows NT Undelete Review.