Technical communicators have developed different methodologies for evaluating the effectiveness of their work (whether the information can be used by the intended audience), such as editing, usability testing, and determining the value-added. But, as vastly differing assessments of the same professionally produced technical communication products suggest, at least three broad value systems underlie the assessment practices: characteristic-based (assessing against a set of criteria), task-based (assessing users' observed ability to perform tasks), and results-based (assessing the contribution to the publisher, usually in financial terms). The systems do not overlap with one another; rather, they embody different values about what makes technical communication effective. The most complete form of assessment may involve multiple assessment approaches and triangulated results.

This article explores the design choices for Network Earth, a museum exhibit that introduced the general public to computer networks and related issues. The exhibit was one of three studied in a larger research project to develop a grounded model of design for learn-ing in museums. Network Earth was developed by a team that had neither formal train-ing nor academic credentials usually associated with museum exhibits. Although the design process and some of the general goals were similar to those at other sites studied and in the literature, certain practices differed. The team excluded historical objects, let donors influence content, and used different terminology. These differences appear to be cultural. With a limited affiliation with the occupational culture of museum exhibit design, the Network Earth team made choices that were more consistent with the culture of high technology—the subject of the museum and the industry that provided most of its financial support.